Return-Path: Delivered-To: craig@sbc-85.com Received: from gator4254.hostgator.com by gator4254.hostgator.com with LMTP id mBPpOHUj12jMTg4AcizydQ (envelope-from ) for ; Fri, 26 Sep 2025 18:36:21 -0500 Return-path: Envelope-to: craig@sbc-85.com Delivery-date: Fri, 26 Sep 2025 18:36:21 -0500 Received: from p-impout005aa.msg.pkvw.co.charter.net ([47.43.26.136]:36962 helo=p-impout005.msg.pkvw.co.charter.net) by gator4254.hostgator.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.1) (envelope-from ) id 1v2HzA-000000045DJ-1xdi for craig@sbc-85.com; Fri, 26 Sep 2025 18:36:21 -0500 Received: from GeorgeAdams ([74.131.139.95]) by cmsmtp with ESMTPA id 2HyyvNuaU8OhM2HyzvFerX; Fri, 26 Sep 2025 23:36:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cinci.rr.com; s=c20240129; t=1758929769; bh=dULb6FKWC4lmeGuUwQr1cc/ErCmp0Dt6AVJrdQ6nMbE=; h=From:To:References:In-Reply-To:Subject:Date; b=FgQhlfoXy/c8C9MdJU/rBQBv0vQy8yfwSXlENrCZXVFHQVE9js25+CW5Wh4mj8pJU X4dbzKoDKf2FZ8utkcSi1G+LkJaLntlHufhZOmVOpOweGafCQNFMb7eBvnqknlpwqO wKFFwwr1k3jRGpSPmUVaJ8wrKylB7ckFdtqlu5c9ttt85po1YY2CYQpXYcY7TTdDbu 1yF6kJDleuLrVnrlwcF/V6lC8mnPK3BmgdoXSZOAz1fj4iztzjW4UmGBywhaTVYn7A E5LfGFt0cfGTH00Acz5RDVjbc/ApiaDUnS2ln7E8tM0Tj3xcjMo89Gw1thNGgy+vHu P0FmqxAavTZeQ== X-Authority-Analysis: v=2.4 cv=GbcRnxXL c=1 sm=1 tr=0 ts=68d72369 a=hl8TJCE9z2sxp+2MqBjxnA==:117 a=hl8TJCE9z2sxp+2MqBjxnA==:17 a=DAwyPP_o2Byb1YXLmDAA:9 a=whqczNdAAAAA:8 a=NEAV23lmAAAA:8 a=_6GpL_ENAAAA:8 a=HjitWDSJAAAA:8 a=ayC55rCoAAAA:8 a=JhxoAmxK0EaE3rRXJGsA:9 a=gP3hv6B4sLMF96KI:21 a=QEXdDO2ut3YA:10 a=ATClE4nxGrkA:10 a=yMhMjlubAAAA:8 a=SSmOFEACAAAA:8 a=ybPdrOfR1UczASPfWEEA:9 a=SgmwG6yXX2go-6wW:21 a=gKO2Hq4RSVkA:10 a=UiCQ7L4-1S4A:10 a=hTZeC7Yk6K0A:10 a=frz4AuCg-hUA:10 a=lqcHg5cX4UMA:10 a=7sM52Zl38G0TKtPgL8Tb:22 a=IB1QFG2aBfq3amWdyr0s:22 From: To: "'SBC-85'" References: <000001dc2dbb$5d784690$1868d3b0$@cinci.rr.com> <2240FE15-D673-4453-92D9-14C7710BA1A4@sbc-85.com> In-Reply-To: <2240FE15-D673-4453-92D9-14C7710BA1A4@sbc-85.com> Subject: RE: nibbler power up and test Date: Fri, 26 Sep 2025 19:36:07 -0400 Message-ID: <000601dc2f3e$55b22b90$011682b0$@cinci.rr.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01DC2F1C.CEAA0170" X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQHsyQVU/lduPLlkoD6JPl0mK5/VJwHY4zsmtHYhPhA= Content-Language: en-us X-Antivirus: Avast (VPS 250926-6, 9/26/2025), Outbound message X-Antivirus-Status: Clean X-CMAE-Envelope: MS4xfFGKLK+SoSq13LipXhVNuN0e+IopKDPvO3fdjK1eE7HtsQGcUHjgy8lT/NNU9z/uYLOW+5yDG0sGTIHmEqenx3xD5myZBgTDFdE2oXxvZD9r9nBRHQHP 2aiMOZEMi2XTVMRpNEH6aDI+AwFWY1IKhktMIFRFdIIO2zs7G0vggZNIprj39v3oHoHGWZ5mOW0pOg== X-Spam-Status: No, score=-4.3 X-Spam-Score: -42 X-Spam-Bar: ---- X-Spam-Flag: NO This is a multipart message in MIME format. ------=_NextPart_000_0007_01DC2F1C.CEAA0170 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Craig, I wanted to let you know the boards arrived safely today. Thanks for the ba= ckplane and memory card. Any suggestions as to the 72 pin edge connector pa= rt number (or the pin spacing) used on the backplane? Also, I wanted to Thank You for the effort you put into finding the issue w= ith the eproms. I didn=E2=80=99t expect that to be a problem. Hopefully a new eprom programmer will prevent any future problems. I will be interested to see your troubleshooting video. Thanks Again. Regards, George From: SBC-85 Sent: Wednesday, September 24, 2025 10:17 PM To: adamsgl@cinci.rr.com Subject: Re: nibbler power up and test It took several erase cycles before the eprom was blank, so maybe that was = a problem too. I put your boards in the mail today On Sep 24, 2025, at 6:26=E2=80=AFPM, adamsgl@cinci.rr.com wrote: =EF=BB=BF Craig, The eprom issue appears to be from the minipro programmer I have. It does n= ot produce the correct VPP voltage when programming (set for 21 volts and i= t produces 18v). As a result, the eprom appears to program correctly, and w= ill verify correctly. I checked the eprom after a few hours, and the contents did not verify. I = thought maybe the eprom was bad but the same result occurred on one other. = So the end result is a new programmer is in order. I selected the T48 from = XGecu. Hopefully this fixes the problem. Regards, George From: craig@sbc-85.com > Sent: Thursday, September 18, 2025 8:12 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Hi George, So the good news is I don=E2=80=99t think there is a problem with your boar= d. I finally put your eproms in my board and it would not fire up so I checked= their contents. Below are the roms is the high rom. My copy of NIBL is o= n the left, your EPROM on the right. I think you have a bad bit in this e= prom. 0x01 should be C2 but it is C3 in yours. Bit 0 stuck high 04 should be 40 but is 41 in yours 0A should be 37, yours is F7 0f should be FE, yours is FF I am erasing your eproms and see if I can program them and then check them = again. Maybe you just have a lazy column of bits or two. I downloaded but= have not checked the low rom, I am just going to erase them both. Look at your hex file to make sure it matches the list file in the manual. From: craig@sbc-85.com > Sent: Thursday, September 18, 2025 4:47 PM To: 'adamsgl@cinci.rr.com' > Subject: RE: nibbler power up and test I ran various diagnostics on your board with my new program. everything se= emed to check out but it still would not run NIBL. So I put in my NIBL epr= oms, see below. Investigating further=E2=80=A6. But your board is alive. From: adamsgl@cinci.rr.com > Sent: Thursday, September 18, 2025 12:47 PM To: craig@sbc-85.com Subject: RE: nibbler power up and test Craig, Initially I used power up, (got tired of that) but wasn=E2=80=99t sure if t= he reset was sufficient, so I placed a button on U1A-1,2 and the other side= to ground. This seemed to successfully reset the chip. I could then hold t= he chip in reset as long as I wanted. Regards, George From: craig@sbc-85.com > Sent: Thursday, September 18, 2025 2:42 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Hi George, Do you have a reset button on the nibbler that you use after power up? Or = just relying on the power up to cause a reset? Regards craig From: craig@sbc-85.com > Sent: Tuesday, September 16, 2025 2:04 PM To: 'adamsgl@cinci.rr.com' > Subject: RE: nibbler power up and test Hi George, I have been working on my diagnostic utility so I haven=E2=80=99t gotten to= your board yet. However, one round of testing the utility I decided to po= p it in your board so I could tell you something. After several resets, the= utility program started and sent out the command prompt. I then started a= memory test and it found the first block of RAM. So the board works at some level. I will let you know as I have more. From: adamsgl@cinci.rr.com > Sent: Saturday, September 13, 2025 4:28 PM To: craig@sbc-85.com Subject: RE: nibbler power up and test Craig, You are welcome to use the board in your videos. The more troubleshooting s= kills you present, the more everyone benefits. Just blur out the name and address I put on it. Good old ebay parts, =E2=80=98removed from working system=E2=80=99. Good st= ory. Will be interesting to see what you find on my board. Nice video (#143) on the status of the nibbler workalikes. I am really inte= rested in the eprom board. I would like to see the i/o board, with the nati= onal i/o chip and an option to use an 8255 if the national chip is hard to = find. ( I only found one on ebay and it was > $40). Regards, George From: craig@sbc-85.com > Sent: Saturday, September 13, 2025 6:40 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Hi George, Board arrived safely. I am still adding features to my diagnostic code. You are not the only one having trouble getting the board up and running, e= veryone is using scrap chips it seems. Can I use your board for a diagnost= ic video? From: adamsgl@cinci.rr.com > Sent: Wednesday, September 10, 2025 1:28 PM To: craig@sbc-85.com Subject: RE: nibbler power up and test Craig, I sent you the return postage ($12) My testing hardware is the Salea 8 channel logic probe, a logic probe, and = the voltmeter for continuity checks. The programmer I have can also test so= me of the newer chips. The memory scan started at 2000, since the eprom was 0000-1FFF (resulting i= n the P being shown). The assumption I made was write a value, if it didn=E2=80=99t read back the= same then check if it was something other than FF or 00 then it was an epr= om. (shows something is there) Board status, here is what I saw: 4 mhz clock on u1.11 (CLOCK_P2) NRDS was toggling on the processor. Cs0 and cs1 were toggling (not sure why cs1 was, as the code never addresse= d anything (only the lower 24 bytes) where ad10 or 11 were anything but 0, = which should give only cs0)(unless I=E2=80=99m missing something) Also ad12 was always 0. I don=E2=80=99t believe any of the other cs lines were changing. As for the diagnostic code: Yes, using the senseA/B lines to select the test is a good idea, for test1 Good idea for testing only 1 bit and showing the status then continuing bit= by bit to confirm the byte is good. My wish list would be to be able to single step the processor, holding the= status, and address lines in the state to read memory and see what address= is being read from and the value on the data bus. (not readily available s= ince the single step is not in the design). I have used this on the 8085 bo= ards by holding the ready line low. Regards, George From: craig@sbc-85.com > Sent: Wednesday, September 10, 2025 1:58 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Hi George, I actually owe you a few dollars because the last board cost le= ss to send than expected and what you already paypal=E2=80=99d me. It shou= ldn=E2=80=99t cost any more to send back than to send to me. Absolutely get the retro chip tester pro=E2=80=A6 annoying interface but ot= herwise worth every penny. That and my Salea 16ch logic probe I bought the= moment they became available are my goto tools. It will be interesting to see what is wrong with your board, if it is the C= PU or not. Please confirm this is the board status: It is giving a good clock on the output of that AND gate It is toggling NRDS There are various chip selects coming from the decoder and with the test co= de I sent there were no chip selects on the upper half Are there any other data points? The memory scan you showed me, I didn=E2=80=99t see any Ps show up, but I d= on=E2=80=99t see a way to tell if something is prom or empty. I want to bounce some ideas off you regarding the diagnostic code. The critical inputs, NRST, CONT, NENIN,BREQ,NHOLD are all DC and can be con= firmed with a volt meter. The Test 1 that I already sent you that sequences the flags and that will = establish that the CPU can fetch instructions. I should have put a little more thought into this before you shipped the bo= ard=E2=80=A6. If it fails test1 like your board, I think the following can be done to con= firm the CPU is working=E2=80=A6 Remove all buffers, the latch, and the decoder could even remove the AND a= nd NOT chips and patch across U1A on the NRST input. Jumper across the three 81ls97 buffers U8 on the data input, u9 on the low = address, u4 on the high address and signals. Jumper the low ROM U10 chip select to ground and jumper it=E2=80=99s enable= to NRDS. Now the CPU will pull instructions directly from the eprom and the RDS will= avoid bus contention on the data bus during the outgoing address/data cycl= e it is hard to test the 8060 itself without fetching instructions, but if it= has a good clock and is putting out seemingly correct NADS and NRDS strobe= s I think it is a good sign that the CPU is internally functional but it co= uld still have a dead I/O line on the address or data. As far as the most = basic starting test I can=E2=80=99t think of anything simpler Once the user gets past test1 and can fetch instructions, the next key thin= g is if the RAM works. Test1 gives the opportunity to also confirm the ser= ial TxD is working which is just a couple of inverters more than Flag0 work= ing. So starting with test2 I begin sending status to the console. I don= =E2=80=99t send status in test 1 because it makes it harder to diagnose whe= n looking at the waveforms after a reset. Test2 is the first ram test. I search all memory locations and when it fin= ds a single bit of RAM it prints the address to the CO and a dash. By sing= le bit, I literally mean that=E2=80=A6. Only one bit has to work for it to = be a valid ram location=E2=80=A6 in these 1x ram banks, maybe just one ram = chip works. It then continues the test until all 8 bits fail and then it p= rints the ending address of the block. Then a new line is sent to the CO a= nd it repeats. This will tell the user if they have any working ram=E2=80= =A6 even a single bit=E2=80=A6. And it will give them the opportunity to di= agnose that. Test3 is the same as test2 except the full byte of ram must work to be cons= idered a block That is it for the ramless testing, then the diagnostics can start using RA= M and do more detailed memory testing to find bad bits. But I think I will go back and add more fundamental testing before the RAM = testing. Test the sense inputs by doing something different on power up if= the sense a/b input is at logic zero. If they are confirmed working, then= I can accept input from the terminal sooner and let the user select tests.= I know this is a wide ranging email, but let my know your thoughts. Thanks craig From: adamsgl@cinci.rr.com > Sent: Wednesday, September 10, 2025 9:31 AM To: craig@sbc-85.com Subject: RE: nibbler power up and test Craig, I put the board in the mail today. (board should be delivered to you Saturd= ay) The cost to ship was $11 including $100 insurance. Since you are send i= t back with the memory and backplane boards, is $20 enough to cover the cos= t? This is code I did for the serial doodad. Here is what I did for a memory scanner (starts with 2000 as I know the boa= rd has eprom below this address, but ideally should start with 0000) ;2000 ................ ;3000 ................ ;4000 ................ ;5000 ................ ;6000 ................ ;7000 ................ ;8000 ................ ;9000 ................ ;a000 RRRRRRRR ;b000 ................ ;c000 ................ ;d000 ................ ;e000 ................ ;f000 RRRRRRRR. =2E is nothing found R is ram P is eprom Just a thought for complete memory scanner. Regards, George From: craig@sbc-85.com > Sent: Tuesday, September 9, 2025 8:57 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Hi George, Today I messed around trying to get the AS assembler and I couldn=E2=80=99t= get it to run in a dos window so I gave up and installed the sbasm. I hav= e been assembling and it seems to be working ok, once I finally started get= ting used to the syntax that is. It is better than figuring out relative a= ddresses by hand anyway. When I send back your board, I can also send the memory and the backplane s= ince I have those running OK. I think the memory board just has a couple o= f silkscreen errors. I am expanding my ramless test to now go through and do a simple test of th= e onboard RAM=E2=80=A6 at least sending out to CO what blocks of RAM it ca= n identify. So test 1 just does that counting up of the flags. Once the u= ser gets that going then we can send things to the CO and test 2 can identi= fy and print out RAM blocks. Since you have been dinking with a no-workie board, let me know what other = tests would be useful. Regards craig From: adamsgl@cinci.rr.com > Sent: Tuesday, September 9, 2025 4:53 PM To: 'SBC-85' > Subject: RE: nibbler power up and test Craig, I will put the board in the mail tomorrow. After I see what the cost is, I = will paypal you the funds to send it back. I really appreciate you doing th= is!! The board does not appear to have any solder bridges or shorts, so it has t= o be a bad buffer or the 8060 itself. The ramless test was done with no ram installed and only U11 eprom installe= d with the hex code you provided. Nice work on the ramless test program. I went through and figured out how i= t works. I see the pattern you talked about in your last video, load status= register, do something with the bits and write back to the status register= =2E The common theme. I need to work thru the delay calculation in the nex= t day or so. I agree with you on the assembler link I sent you. It needs to be much simp= ler than the one in the like from me. If you find one, let me know. I need to get the retro ship tester you have, since I am getting more and m= ore boards with vintage hardware, and no way to test some of the chips. Got= to wait a bit longer, as the social security only goes so far. Thanks Again for the assistance in getting this running. Regards, George From: SBC-85 > Sent: Monday, September 8, 2025 10:33 PM To: adamsgl@cinci.rr.com Subject: Re: nibbler power up and test Hi George. Just pay to ship it both ways. Make sure you sufficiently insure= it to replace all the components. My mailing address is Craig Andrews 13500 ne 259th street Battle ground, wa 98604 Please put a tag on it with your name and address. I hate to have other pe= ople=E2=80=99s things around in case something happens to me, and family ha= s no idea something on my bench belongs to someone else. Regards Craig On Sep 8, 2025, at 6:40=E2=80=AFPM, adamsgl@cinci.rr.com wrote: =EF=BB=BF Craig, That might be the best way to get this working without having to buy anothe= r 8060 if it=E2=80=99s not needed. Let me know the cost. Regards, George From: craig@sbc-85.com > Sent: Monday, September 8, 2025 9:35 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test The SC/MP folks on the UK vintage radio site seem to be smitten with that a= ssembler. I downloaded it a week or two ago, but have not gone as far as i= nstalling it. I am learning a lot by hand assembling anyway. Here is another assembler that seems way over the top for what I need The Macro Assembler AS I would like just a simple dos prompt assembler like A85 I get from herb an= d use for my 8080/85 projects. If you have no confidence in your chips, I can test them for you. Or your = whole board for that matter From: adamsgl@cinci.rr.com > Sent: Monday, September 8, 2025 6:20 PM To: craig@sbc-85.com Subject: RE: nibbler power up and test Craig, Here is an assembler I found while waiting on parts. https://github.com/sbprojects/sbasm3 Kind of obscure to run it. Needs python 3 and run by =E2=80=98python sbasm.= py=E2=80=99 after getting into the folder where it was downloaded. Then wil= l ask for the file to assemble (a pain) Not sure yet about how close the opcodes are to standard. (look in the sbpr= ojects/test/opcodes folder for an example of the code) Now to find a sc/mp without costing a fortune. Regards, George From: craig@sbc-85.com > Sent: Monday, September 8, 2025 7:26 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Right now this just repeats every 130ms. I think that I will add some RAM = testing to the next version unless you think something else would be more u= seful. I am still hand assembling so it is slow going. From: craig@sbc-85.com > Sent: Monday, September 8, 2025 3:15 PM To: 'adamsgl@cinci.rr.com' > Subject: RE: nibbler power up and test Hi George, This will count the three flag lines from 0 to 7 and then wait 131ms before= repeating From: adamsgl@cinci.rr.com > Sent: Monday, September 8, 2025 1:35 PM To: craig@sbc-85.com Subject: RE: nibbler power up and test Criag, I have an 8 channel logic analyzer and also a logic probe. The clock signal is 4 mhz from u1d.11. Chip selects 0,1,2,3 (eproms) are toggling, no activity on cs 4, 5,6,7 (ram= s) Thanks for the help. George From: craig@sbc-85.com > Sent: Monday, September 8, 2025 4:18 PM To: adamsgl@cinci.rr.com Subject: RE: nibbler power up and test Hi George. Well, that is inconvenient. The nibbler test is part of the ROMs. I think jpb1 is installed and the input to the first inverter is taken low = so sense b will be low. Then it does the test. Do you have a good clock signal? Are you seeing anything on the read strob= e? Seeing anything on the chip selects for the eproms? NIBL is a bit of a problem since everything has to work before anything wil= l work. Hold on a bit, I will write a little ramless test to send you. Do you have= a scope or logic analyzer or logic probe? From: adamsgl@cinci.rr.com > Sent: Monday, September 8, 2025 1:08 PM To: craig@sbc-85.com Subject: nibbler power up and test Craig, I finally got all the parts for the nibbler and completed assembly. With th= at said, it=E2=80=99s time for head scratching. No response on power up. So= I tried the nibbler test in Gordon=E2=80=99s Digikey notes, again with no = luck. The chips I can=E2=80=99t test are the rams (I only have 1k installed, from= the listing in the digikey notes it should be enough) the buffers and the = sc/mp. Chip. Any thoughts on the next steps. I=E2=80=99m guessing the JPB1 jumper needs to be removed to do the nibbler = test. Is the nibbler test part of the code in the eproms or is it in the sc/mp ha= rdware design? (it=E2=80=99s not obvious if its in the eproms) Thanks again for the help. Regards, George Virus-free. www.avast.com Virus-free. www.avast.com -- This email has been checked for viruses by Avast antivirus software. www.avast.com ------=_NextPart_000_0007_01DC2F1C.CEAA0170 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Craig,

 

I wanted to let you = know the boards arrived safely today. Thanks for the backplane and = memory card. Any suggestions as to the 72 pin edge connector part number = (or the pin spacing) used on the backplane?

 

Also, I wanted to = Thank You for the effort you put into finding the issue with the eproms. = I didn=E2=80=99t expect that to be a problem.

Hopefully a new eprom = programmer will prevent any future problems.

 

I will be interested = to see your troubleshooting video.

 

Thanks = Again.

 

Regards,

 

George

 

 

 

From:<= /b> = SBC-85 <craig@sbc-85.com>
Sent: Wednesday, September = 24, 2025 10:17 PM
To: adamsgl@cinci.rr.com
Subject: = Re: nibbler power up and test

 

It took = several erase cycles before the eprom was blank, so maybe that was a = problem too.  I put your boards in the mail = today



On Sep 24, 2025, at 6:26=E2=80=AFPM, adamsgl@cinci.rr.com = wrote:

=EF=BB=BF

=

Craig,

 

The eprom issue = appears to be from the minipro programmer I have. It does not produce = the correct VPP voltage when programming (set for 21 volts and it = produces 18v). As a result, the eprom appears to program correctly, and = will verify correctly.

I checked the eprom after a few hours, =  and the contents did not verify. I thought maybe the eprom was bad = but the same result occurred on one other.

 

So the end result is = a new programmer is in order. I selected the T48 from XGecu. =  Hopefully this fixes the problem.

 

Regards,

 

George

 

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Thursday, September 18, 2025 8:12 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Hi George,

 

So the good news is I = don=E2=80=99t think there is a problem with your board.  =

 

I finally put your = eproms in my board and it would not fire up so I checked their = contents.  Below are the roms is the high rom.  My copy of = NIBL is on the left, your EPROM on the right.   I think you = have a bad bit in this eprom.  0x01 should be C2 but it is C3 in = yours.  Bit 0 stuck high

04 should be 40 but = is 41 in yours

0A should be 37, yours is = F7

0f should be FE, yours is = FF

 

I am erasing your = eproms and see if I can program them and then check them again.  = Maybe you just have a lazy column of bits or two.  I downloaded but = have not checked the low rom, I am just going to erase them = both.

 

Look at your hex file = to make sure it matches the list file in the = manual.

 

<image001.png>

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Thursday, September 18, 2025 4:47 PM
To: = 'adamsgl@cinci.rr.com' <adamsgl@cinci.rr.com>
S= ubject: RE: nibbler power up and = test

 

I ran various diagnostics on your board with = my new program.  everything seemed to check out but it still would = not run NIBL.  So I put in my NIBL eproms, see = below.

Investigating further=E2=80=A6. But your = board is alive.

 

<image002.png>

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Thursday, September 18, 2025 12:47 PM
To: craig@sbc-85.com
Subject: = RE: nibbler power up and test

 

Craig,

 

Initially I used = power up, (got tired of that) but wasn=E2=80=99t sure if the reset was = sufficient, so I placed a button on U1A-1,2 and the other side to = ground. This seemed to successfully reset the chip. I could then hold = the chip in reset as long as I wanted.

 

Regards,

 

George

 

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Thursday, September 18, 2025 2:42 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Hi George,

 

Do you have a reset = button on the nibbler that you use after power up?  Or just relying = on the power up to cause a reset?

 

Regards

craig

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Tuesday, September 16, 2025 2:04 PM
To: = 'adamsgl@cinci.rr.com' <adamsgl@cinci.rr.com>
S= ubject: RE: nibbler power up and = test

 

Hi George,

I have been working = on my diagnostic utility so I haven=E2=80=99t gotten to your board = yet.  However, one round of testing the utility I decided to pop it = in your board so I could tell you something. After several resets, the = utility program started and sent out the command prompt.  I then = started a memory test and it found the first block of RAM.  =

 

So the board works at = some level.

 

I will let you know = as I have more.

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Saturday, September 13, 2025 4:28 PM
To: craig@sbc-85.com
Subject: = RE: nibbler power up and test

 

Craig,

 

You are welcome to = use the board in your videos. The more troubleshooting skills you = present, the more everyone benefits.

 

Just blur out the = name and address I put on it.

 

Good old ebay parts, = =E2=80=98removed from working system=E2=80=99. Good = story.

 

Will be interesting = to see what you find on my board.

 

Nice video (#143) on = the status of the nibbler workalikes. I am really interested in the = eprom board. I would like to see the i/o board, with the national i/o = chip and an option to use an 8255 if the national chip is hard to find. = ( I only found one on ebay and it was > $40).

 

Regards,

 

George

 

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Saturday, September 13, 2025 6:40 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Hi George,

 

Board arrived = safely.  I am still adding features to my diagnostic = code.

You are not the only one having = trouble getting the board up and running, everyone is using scrap chips = it seems.  Can I use your board for a diagnostic = video?

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Wednesday, September 10, 2025 1:28 PM
To: craig@sbc-85.com
Subject: = RE: nibbler power up and test

 

Craig,

 

I sent you the return = postage ($12)

 

My testing hardware = is the Salea 8 channel logic probe, a logic probe, and the voltmeter for = continuity checks. The programmer I have can also test some of the newer = chips.

 

The memory scan = started at 2000, since the eprom was 0000-1FFF (resulting in the P being = shown).

The assumption I made was write a value, if = it didn=E2=80=99t read back the same then check if it was something = other than FF or 00 then it was an eprom. (shows something is = there)

 

Board status, here is = what I saw:

4 mhz clock on u1.11 = (CLOCK_P2)

NRDS was toggling on the = processor.

Cs0 and cs1 were toggling (not sure why cs1 = was, as the code never addressed anything (only the lower 24 bytes) = where ad10 or 11 were anything but 0, which should give only cs0)(unless = I=E2=80=99m missing something)

Also ad12 was always = 0.

I don=E2=80=99t believe any of the other cs = lines were changing.

 

As for the diagnostic = code:

 

Yes, using the = senseA/B lines to select the test is a good idea, for = test1

 

Good idea for testing = only 1 bit and showing the status then continuing bit by bit to confirm = the byte is good.

 

My wish list would be =  to be able to single step the processor, holding the status, and = address lines in the state to read memory and see what address is being = read from and the value on the data bus. (not readily available since = the single step is not in the design). I have used this on the 8085 = boards by holding the ready line low.

 

Regards,

 

George

 

 

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Wednesday, September 10, 2025 1:58 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Hi George,  I actually owe you a few = dollars because the last board cost less to send than expected and what = you already paypal=E2=80=99d me.  It shouldn=E2=80=99t cost any = more to send back than to send to me.

 

Absolutely get the = retro chip tester pro=E2=80=A6 annoying interface but otherwise worth = every penny.  That and my Salea 16ch logic probe I bought the = moment they became available are my goto tools.

 

 

It will be = interesting to see what is wrong with your board, if it is the CPU or = not.  Please confirm this is the board = status:

It is giving a good clock on the output of = that AND gate

It is toggling NRDS

There are various = chip selects coming from the decoder and with the test code I sent there = were no chip selects on the upper half

Are there any other = data points?

 

The memory scan you = showed me, I didn=E2=80=99t see any Ps show up, but I don=E2=80=99t see = a way to tell if something is prom or empty.

 

I want to bounce some = ideas off you regarding the diagnostic code. =  

The critical inputs, NRST, CONT, = NENIN,BREQ,NHOLD are all DC and can be confirmed with a volt = meter.

 

The  Test 1 that = I already sent you that sequences the flags and that will establish that = the CPU can fetch instructions. 

 

I should have put a = little more thought into this before you shipped the = board=E2=80=A6. 

 

If it fails test1 = like your board, I think the following can be done to confirm the CPU is = working=E2=80=A6

Remove all buffers, the latch, and the = decoder  could even remove the AND and NOT chips and patch across = U1A on the NRST input.

Jumper across the three 81ls97 buffers U8 on = the data input, u9 on the low address, u4 on the high address and = signals.

Jumper the low ROM U10 chip select to ground = and jumper it=E2=80=99s enable to NRDS. 

Now the CPU will pull = instructions directly from the eprom and the RDS will avoid bus = contention on the data bus during the outgoing address/data = cycle

 

it is hard to test = the 8060 itself without fetching instructions, but if it has a good = clock and is putting out seemingly correct NADS and NRDS strobes I think = it is a good sign that the CPU is internally functional but it could = still have a dead I/O line on the address or data.  As far as the = most basic starting test I can=E2=80=99t think of anything = simpler

 

Once the user gets = past test1 and can fetch instructions, the next key thing is if the RAM = works.  Test1 gives the opportunity to also confirm the serial TxD = is working which is just a couple of inverters more than Flag0 = working.  So starting with test2 I begin sending status to the = console.  I don=E2=80=99t send status in test 1 because it makes it = harder to diagnose when looking at the waveforms after a = reset.

 

Test2 is the first = ram test.  I search all memory locations and when it finds a single = bit of RAM it prints the address to the CO and a dash.  By single = bit, I literally mean that=E2=80=A6. Only one bit has to work for it to = be a valid ram location=E2=80=A6 in these 1x ram banks, maybe just one = ram chip works.  It then continues the test until all 8 bits fail = and then it prints the ending address of the block.  Then a new = line is sent to the CO and it repeats.  This will tell the user if = they have any working ram=E2=80=A6 even a single bit=E2=80=A6. And it = will give them the opportunity to diagnose that.

 

Test3 is the same as = test2 except the full byte of ram must work to be considered a = block

 

That is it for the = ramless testing, then the diagnostics can start using RAM and do more = detailed memory testing to find bad bits.

 

But I think I will go = back and add more fundamental testing before the RAM testing.  Test = the sense inputs by doing something different on power up if the sense = a/b input is at logic zero.  If they are confirmed working, then I = can accept input from the terminal sooner and let the user select = tests.

 

I know this is a wide = ranging email, but let my know your thoughts.

 

Thanks

craig

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Wednesday, September 10, 2025 9:31 AM
To: craig@sbc-85.com
Subject: = RE: nibbler power up and test

 

Craig,

 

I put the board in = the mail today. (board should be delivered to you Saturday) The cost to = ship was $11 including $100 insurance. Since you are send it back with = the memory and backplane boards, is $20 enough to cover the = cost?

 

This is code I did = for the serial doodad.

Here is what I did for a memory scanner = (starts with 2000 as I know the board has eprom below this address, but = ideally should start with 0000)

;2000 = ................

;3000 = ................

;4000 = ................

;5000 = ................

;6000 = ................

;7000 = ................

;8000 = ................

;9000 = ................

;a000 RRRRRRRR

;b000 = ................

;c000 = ................

;d000 = ................

;e000 = ................

;f000 RRRRRRRR.

 

. is nothing = found

R is ram

P is = eprom

 

Just a thought for = complete memory scanner.

 

Regards,

 

George

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Tuesday, September 9, 2025 8:57 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Hi George,

 

Today I messed around = trying to get the AS assembler and I couldn=E2=80=99t get it to run in a = dos window so I gave up and installed the sbasm.  I have been = assembling and it seems to be working ok, once I finally started getting = used to the syntax that is.  It is better than figuring out = relative addresses by hand anyway.

 

When I send back your = board, I can also send the memory and the backplane since I have those = running OK.  I think the memory board just has a couple of = silkscreen errors.

 

I am expanding my = ramless test to now go through and do a simple test of the onboard = RAM=E2=80=A6  at least sending out to CO what blocks of RAM it can = identify.  So test 1 just does that counting up of the flags.  = Once the user gets that going then we can send things to the CO and test = 2 can identify and print out RAM blocks.

 

Since you have been = dinking with a no-workie board, let me know what other tests would be = useful.

 

Regards

craig

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Tuesday, September 9, 2025 4:53 PM
To: = 'SBC-85' <craig@sbc-85.com>
Subject:<= /b> RE: nibbler power up and test

 

Craig,

 

I will put the board = in the mail tomorrow. After I see what the cost is, I will paypal you = the funds to send it back. I really appreciate you doing = this!!

 

The board does not = appear to have any solder bridges or shorts, so it has to be a bad = buffer or the 8060 itself.

 

The ramless test was = done with no ram installed and only U11 eprom installed with the hex = code you provided.

 

Nice work on the = ramless test program. I went through and figured out how it works. I see = the pattern you talked about in your last video, load status register, = do something with the bits and write back to the status register. The = common theme.  I need to work thru the delay calculation in the = next day or so.

 

I agree with you on = the assembler link I sent you. It needs to be much simpler than the one = in the like from me. If you find one, let me = know.

 

I need to get the = retro ship tester you have, since I am getting more and more boards with = vintage hardware, and no way to test some of the chips. Got to wait a = bit longer, as the social security only goes so = far.

 

Thanks Again for the = assistance in getting this running.

 

Regards,

 

George

 

 

From:<= /b> = SBC-85 <craig@sbc-85.com> =
Sent: Monday, September 8, 2025 10:33 PM
To: adamsgl@cinci.rr.com
Subje= ct: Re: nibbler power up and = test

 

Hi = George. Just pay to ship it both ways. Make sure you sufficiently insure = it to replace all the components.

 

My mailing address is

Craig Andrews

13500 ne 259th street

Battle ground, wa

98604

 

Please put a tag on it with your name and address. =  I hate to have other people=E2=80=99s things around in case = something happens to me, and family has no idea something on my bench = belongs to someone else.

Regards

 

Craig 

 

On Sep 8, 2025, at 6:40=E2=80=AFPM, adamsgl@cinci.rr.com = wrote:

=EF=BB=BF

=

Craig,

 

That might be the = best way to get this working without having to buy another 8060 if = it=E2=80=99s not needed. Let me know the cost.

 

Regards,

 

George

 

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Monday, September 8, 2025 9:35 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

The SC/MP folks on the UK vintage radio site = seem to be smitten with that assembler.  I downloaded it a week or = two ago, but have not gone as far as installing it.  I am learning = a lot by hand assembling anyway.

Here is another = assembler that seems way over the top for what I = need

The Macro Assembler = AS

 

I would like just a = simple dos prompt assembler like A85 I get from herb and use for my = 8080/85 projects.

 

If you have no = confidence in your chips, I can test them for you.  Or your whole = board for that matter

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Monday, September 8, 2025 6:20 PM
To: craig@sbc-85.com
Subject: = RE: nibbler power up and test

 

Craig,

Here is an assembler = I found while waiting on parts.

 

https://github.com/sbprojec= ts/sbasm3

 

Kind of obscure to = run it. Needs python 3 and run by =E2=80=98python sbasm.py=E2=80=99 = after getting into the folder where it was downloaded. Then will ask for = the file to assemble (a pain)

 

Not sure yet about = how close the opcodes are to standard. (look in the = sbprojects/test/opcodes folder for an example of the = code)

 

Now to find a sc/mp = without costing a fortune.

 

Regards,

 

George

 

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Monday, September 8, 2025 7:26 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Right now this just repeats every = 130ms.  I think that I will add some RAM testing to the next = version unless you think something else would be more useful.  I am = still hand assembling so it is slow going.

 

<image001.png>

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Monday, September 8, 2025 3:15 PM
To: = 'adamsgl@cinci.rr.com' <adamsgl@cinci.rr.com>
S= ubject: RE: nibbler power up and = test

 

Hi George,

 

This will count the = three flag lines from 0 to 7 and then wait 131ms before = repeating

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Monday, September 8, 2025 1:35 PM
To: craig@sbc-85.com
Subject: = RE: nibbler power up and test

 

Criag,

 

I have an 8 channel = logic analyzer and also a logic probe.

 

The clock signal is 4 = mhz from u1d.11.

 

Chip selects 0,1,2,3 = (eproms) are toggling, no activity on cs 4, 5,6,7 = (rams)

 

Thanks for the = help.

 

George

 

From:<= /b> craig@sbc-85.com <craig@sbc-85.com> =
Sent: Monday, September 8, 2025 4:18 PM
To: adamsgl@cinci.rr.com
Subje= ct: RE: nibbler power up and = test

 

Hi George.  Well, that is = inconvenient.

 

The nibbler test is = part of the ROMs.

 

I think jpb1 is = installed and the input to the first inverter is taken low so sense b = will be low.  Then it does the test.

 

Do you have a good = clock signal?  Are you seeing anything on the read strobe?  = Seeing anything on the chip selects for the = eproms?

 

NIBL is a bit of a = problem since everything has to work before anything will = work.

 

Hold on a bit, I will = write a little ramless test to send you.  Do you have a scope or = logic analyzer or logic probe?

 

From:<= /b> adamsgl@cinci.rr.com <adamsgl@cinci.rr.com> =
Sent: Monday, September 8, 2025 1:08 PM
To: craig@sbc-85.com
Subject: = nibbler power up and test

 

Craig,

 

I finally got all the = parts for the nibbler and completed assembly. With that said, = it=E2=80=99s time for head scratching. No response on power up. So I = tried the nibbler test in Gordon=E2=80=99s Digikey notes, again with no = luck.

The chips I can=E2=80=99t test are the rams = (I only have 1k installed, from the listing in the digikey notes it = should be enough) the buffers and the sc/mp. Chip. Any thoughts on the = next steps.

 

I=E2=80=99m guessing = the JPB1 jumper needs to be removed to do the nibbler = test.

 

Is the nibbler test = part of the code in the eproms or is it in the sc/mp hardware design? = (it=E2=80=99s not obvious if its in the eproms)

 

Thanks again for the = help.

 

Regards,

 

George

 

 

 

 

 

 

V= irus-free.www.avast.com

 

 

 

V= irus-free.www.avast.com

 

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