Return-Path: Delivered-To: craig@sbc-85.com Received: from gator4254.hostgator.com by gator4254.hostgator.com with LMTP id oDyaLjX7G2OqZA4AcizydQ (envelope-from ) for ; Fri, 09 Sep 2022 21:49:25 -0500 Return-path: Envelope-to: craig@sbc-85.com Delivery-date: Fri, 09 Sep 2022 21:49:25 -0500 Received: from mout.perfora.net ([74.208.4.196]:39669) by gator4254.hostgator.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oWqYP-0040Pb-QP for craig@sbc-85.com; Fri, 09 Sep 2022 21:49:25 -0500 Received: from DESKTOPD1S599H ([70.15.0.2]) by mrelay.perfora.net (mreueus004 [74.208.5.2]) with ESMTPSA (Nemesis) id 1M5Pdx-1oXftn0xbZ-001UZL for ; Sat, 10 Sep 2022 04:48:58 +0200 From: To: "'SBC-85'" References: <01d901d8c3d2$0964f770$1c2ee650$@jjwhitney.com> In-Reply-To: Subject: RE: SBC-85 plus new project board Date: Fri, 9 Sep 2022 22:48:57 -0400 Message-ID: <019601d8c4bf$e00967a0$a01c36e0$@jjwhitney.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0197_01D8C49E.58FE5750" X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQKZ3td106LCwnxTCaROWAv8EkCMwAGYGLYYrEkAHrA= Content-Language: en-us X-Provags-ID: V03:K1:2BDepcb8HQLZqBKnDZLX8/yWsDW5lvh1Q9ZyyvwLZI2bVWl94pG D1nIyBzsj1FcslvTjrRct503GB6bguMIZXQgVHgPLo/A3Lwt1nSV0acbV2yLXEGI0hXLPAg F8muioI1qZWYmHVxpHZ3aXClHXqukQhOWWhACS8wyzgSmQIMU4j4BC1ZKhjwDIpoedZfv+k zhUrl4nIl5iSRsFbPMkRg== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:z3WhJWG5WRo=:2yzuo3ZfkKDED8gmcCmqqI uNvYvwFN3S+L4a2YXbp+FIrukXvUiEiWZ0JQE4FMqXtKZitJoK0IHgwNvQ8EwFEUvMlv4TvWL 7JEMaxtrK3VVwK6aGFRuLnANcSDiRrkuYx2QSOfVJE3lL22SC/pMKW81S+PyGXciS0U4GZ/Dc AP4UL8mBrx6YUK68Wi7toR3hSBoOo1XnnVG9bHJEFSISlGyeXUyCOfsZNXpo8RUE0+JO966E7 lczh4KWEEqHSfo8wJ/yhy0LUrhbTRbO6MvIhEY4ESQ6bUouKWtEYXd8wkD4mArBJ9mW/tEpbD kILKgJGRHbQXLWvrU5cGn/6C/vK7D7/D/pVhqFxRyr+sYZBDCHtOEPx+CjVIkktsjyHO3mySr B123ykDzYWP7jcHJYGE1/XWNL1kARiecls81eVOwp+gZc4UtEJyk+XD0TlxfhmOETCQRGy5X1 GO8LaxDwHmdAhfnB9PRFnDt5ClAh5MyO7LU+lTsplcwnJv15vfnK5D+XY3g14PtODGJXyA958 I8MJn2EcfOi0eh+J0eVVqwDrChFWzWdBOOiiB/7qjtmvm9PlsXdC17uZ4zIwC1lWSQtvxxdoV MSkatYsO8qQR1ShPMfUIF5QJGQrjw34t3PhgnFx+NsFH+gkAlAiFUICE7pdfc8MQkpLCbiuHz CF+Dnfx7hdFQX4B4u7oe4MgpW+cX42af79geU92JpfFGvyX7MnadXI8njzqmKHBONdkS7M/Ee IZY8+w6jwU4Acwyz7MmAis2/u9TvVHWIWG236olx9lr7/RZqN9Gzxy+/kX2G+ofs1yleB9Si1 1vtmBto X-Spam-Status: No, score=0.0 X-Spam-Score: 0 X-Spam-Bar: / X-Spam-Flag: NO This is a multipart message in MIME format. ------=_NextPart_000_0197_01D8C49E.58FE5750 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hi Craig: =20 I have a limited set of test instruments so I may not be able to = check everything effectively. I need to dig up my frequency counter to = see if the crystal is working. I may have a bad batch of crystals so I = will find another way to get the baud rate signal to the board. I have = some ideas on how I can check that stuff and I will let you know what I = find. Since both boards are doing the same thing it may very well be the = crystal on both boards is not working. =20 Jack =20 From: SBC-85 =20 Sent: Thursday, September 08, 2022 11:56 PM To: john@jjwhitney.com Subject: Re: SBC-85 plus new project board =20 Writing commands and getting response should be fundamental, you are = right that is the place to start. =20 Are you using 8251 or 8251A? =20 You have I/o with the PPI, so Board decoding must be ok but if you can = confirm /CE with a scope or logic probe that would be worth the effort. Can you put a scope or logic probe on and make sure /rd /wr reset A8 are = the same on the UART and PPI? Do you have a good CLK at the UART? The PPI doesn=E2=80=99t need a CLK, = but the UART needs it to work.=20 =20 =20 On Sep 8, 2022, at 3:26 PM, john@jjwhitney.com = wrote: =EF=BB=BF Hi Craig: =20 I had the chance to try the SPIO board today and can not get the = serial port to work. The other ports work as expected but I get no = response from the 8251 when I send data to it. I used the confidence = test to send data to the port and the response back was all zeros where = your documents show different responses. When I do an input to the = control register of the 8251 I get only zeros back. I tried two = different boards and 3 different 8251 chips with the same results each = time.=20 =20 I do not know what to try next. Any suggestions? =20 Jack =20 From: craig@sbc-85.com >=20 Sent: Wednesday, September 07, 2022 6:28 PM To: john@jjwhitney.com =20 Subject: RE: SBC-85 plus new project board =20 Hi Jack,=20 I see another tindie order including the SPIO. Are you still having = trouble getting those going properly? Maybe I need to take some time to = look into it and see what could be going wrong? if you are having = troubles, let me know what you are seeing and maybe I can figure out = what is going on. =20 regards =20 craig =20 From: john@jjwhitney.com = >=20 Sent: Sunday, August 7, 2022 1:14 PM To: craig@sbc-85.com =20 Subject: RE: SBC-85 plus new project board =20 Hi Craig: =20 Glad to hear you are back at it. I never got the original bus = monitor to work 100%, had trouble with the single stepping, so I decided = to try the new version of the board. I really like the idea of having a = front panel with flashing LEDs. I retired last month and will be looking = for things to keep busy and building boards is something I enjoy, at = least as long as I can see up close.=20 =20 I never got the serial port to work. I think it had to do with hand = shaking, I gave it some thought and when I try again I will tie CTS & = RTS together on both ends and see if that works. I haven=E2=80=99t look = at the code in maybe two years so it will take me some time to get back = into it and know what I=E2=80=99m doing.=20 =20 If you have an extra STD-bus board I can take a look and see what I = can do with it. I have no experience with that interface so the board = would be operated in stand alone configuration. I watched the video you = sent and will have to look up the project to get additional info. Thanks = for the offer and I hope I can help with the project. Let me know if I = can help down the road. =20 Jack =20 From: craig@sbc-85.com >=20 Sent: Sunday, August 07, 2022 12:58 PM To: john@jjwhitney.com =20 Subject: SBC-85 plus new project board =20 Hi Jack, I see you got another bus monitor board from tindie. =20 Did we finish up this discussion / problem on the SPIO board or did I = drop off the edge of the earth? I am trying to remember last = august---since august can be good flying weather, sometimes when I come = back from a long trip, I totally forget where I was =20 If you would use it, I can send you one of the new STD-85 boards I just = finished. it is STD-bus but it has a few fun features and I could = always use your help finding problems with the board / software / = documentation. =20 {93} STD Bus 8085 Single Board Computer First Round of Testing--Getting = to know the STD-85 - YouTube = =20 =20 if you need another project, I can toss it into the envelope. Or, if = you are looking for a real change of pace, I think I have one of my F8 = boards left I could send. =20 let me know =20 best regards, =20 craig =20 From: john@jjwhitney.com = >=20 Sent: Sunday, August 8, 2021 5:31 AM To: 'craig Andrews' > Subject: RE: SBC-88 =20 Hi Craig: =20 My most recent projects include a Z80 CP/M system based on the = RC2014 platform as well as the Glitch works 8085 CP/M system. I just got = the Z80 working this weekend and finding a lot of cool stuff from the = 1980=E2=80=99s again. The storage system is a 64MB compact flash drive = and the 100 pin bus has many different cards to add to it. The Glitch = works 8085 is a bit more limited but has some expansion capabilities. = Over all I think your bus structure is better and if you have thoughts = of adding a compact flash card for storage they are fairly easy to = implement. Only problem is the fine pitch surface mount card holder.=20 =20 One other project is I am trying, yet again, to grow Bonsai trees. = It is a fascinating hobby but very challenging to start a tree from a = seed and have it grow to a sustainable size. I have had success in = germinating a few trees only to have them all die at some point, some = lasting many months but all seem to succumb to neglect. Maybe as I get = in to retirement I will have more time to pay attention to them. =20 As for the needed corrections, I still could not get the 8251 on = the SP/IO board to work. Might have something to do with CTS/RTS signals = but I=E2=80=99m not sure. I am looking forward to reviewing you future = projects so please let me help when you need a second pair of eyes. Stay = healthy and productive and I look forward to hearing from you soon. =20 Jack Whitney =20 From: craig Andrews >=20 Sent: Wednesday, August 04, 2021 11:48 PM To: john@jjwhitney.com =20 Subject: Re: SBC-88 =20 Hi Jack, it is good to hear from you. I am slowly getting back into = things but have not been working on electronics much. For some reason = starting (and then finishing) projects seem like a major hurdle. =20 If you have come across any things in the documentation that I need to = address, please let me know. Those are little projects that are easy = for me to get traction.=20 =20 I cannot remember if I caught up on all corrections on the hardware like = the dangling ground you found on the serial port. So let me know if you = are seeing any hardware problems too. =20 =20 If you are looking for software projects, the version of tiny basic on = the sbc-85 site is still incomplete. =20 yes, there is a lot of good, clean fun left in the 8085 still yet. =20 What projects are you up to? =20 Regards =20 Craig =20 On Aug 4, 2021, at 7:02 PM, john@jjwhitney.com = wrote: =EF=BB=BF Hi Craig: =20 Long time since we last connected. So glad you are better now and = wish you the best moving forward. I was a bit worried since you went = from a prolific poster to nothing so suddenly. Sorry to hear about you = contacting Covid-19, I hope you are fully recovered or close to it. I = know I asked about the 8088 system before but now I=E2=80=99m hooked on = the 8085 and built a few different versions and having a lot of fun. = Thanks for sending me down that road as I have learned a lot along the = way.=20 =20 Take care and keep me informed of your next project. I wish you all = the best. =20 Jack Whitney =20 From: craig.andrews@tessol-inc.com = >=20 Sent: Friday, September 11, 2020 7:43 PM To: john@jjwhitney.com =20 Subject: RE: SBC-88 =20 Just discovered there is a mistake in the SBC-85 v2 =20 Pin 5 of the DB9 was left floating, that needs to be taken to ground =20 Regards =20 Craig =20 =20 From: john@jjwhitney.com = >=20 Sent: Sunday, August 23, 2020 6:51 AM To: guus.assmann@wolmail.nl =20 Cc: craig.andrews@tessol-inc.com =20 Subject: RE: SBC-88 =20 Hi Guus: =20 I was able to look at the items you sent. As for the buss structure = I believe it will work as described. The only change would be to change = the TRAP pin to NMI and connect the NMI pin to it. Both have the same = function on their respective CPU=E2=80=99s, just the naming difference. =20 I downloaded the KiCad program and am working on a new schematic = for the 8088 circuit. It will take me a while as I have to learn how the = program works and how to make it all look good.=20 =20 As for the circuit, I am not a fan of using a Mega chip in support = of the design. Reason is simple, I am more of an old school design type. = With the expansion capability of the SBC-85 bus design I see the = possibility of recreating an IBM clone type of system if someone so = desires. As with any old time CPU design the question of why comes to = mind and I say because there is a lot to learn from the old stuff and it = is far more simple to build than any new concept.=20 =20 Give me a few days to discover the KiCad program and I will try to = get the CPU schematic design done. From there I will look into a circuit = board design as well. I am a fan of using four layer PC boards even = though they are more expensive to build. I like the grounding effects = the internal layers provide and not having to route the power and ground = lines helps keep the number of feed through holes to a minimum. Please = keep in mind that these are my preferences and not an absolute for or = against any other design. By using a common bus it is possible for the = universe of potential designs to coexist and the use of various = expansion boards to be built. Keep in touch and thanks for the input. =20 Jack =20 From: guus.assmann@wolmail.nl = >=20 Sent: Saturday, August 22, 2020 1:46 PM To: john@jjwhitney.com =20 Cc: craig.andrews@tessol-inc.com =20 Subject: RE: SBC-88 =20 Hello Jack,=20 =20 Thanks for the reply.=20 Great that you're also willing to participate.=20 I've done quite a bit of PCB routing, so that's not the problem.=20 However it's always good if someone can check the stuff I've done.=20 I've printed the schematics from KiCad. (It's a free program, so you = might want to download it anyway.)=20 The schematics were taken from a Hackaday project. I'll put those = schematics in the mail as well.=20 First thing that would help a lot, is if you can compare the two = schematics and also have a look at the project on Hackaday.=20 =20 Why did I select this?=20 Well, the hackaday project has been tested and has a lot of software.=20 Using the ISP interface on the Atmel Mega is not too complicated.=20 But of course, one of the Ram's can be replaced bay an Eprom.=20 And for that Hackaday project, there's a PCB, so I can test that PCB and = the one I've made.=20 It has an IIC bus for adding a RTC and an SD-interface.=20 But I thing the PCB-design is compattible enough to fit to the SBC-Bus.=20 Also a lot of RAM and any Eprom content can come from the Mega, fetching = it from the SD-card. So very flexible.=20 Still, I/O can be added with the bus. And the RS232 interface can stay = on as well. All parts do fit the PCB. The only thing I've not put on = (yet) is the IIC-expander MCP23017.=20 This design doesn't need the 8284 clock chip and the Mega does the Uart = stuff.=20 =20 One more thing I've done as preparation is make a document on the = expansion bus connector. We need to determine the signals and what to = add on the bus. The where to add it should be a bit logical as well. But = routing is not always so easy....=20 Could you also please check these two documents. There's something = missing still, I've not added all the stuff.=20 =20 Anyway, think about it.=20 And please don't hold back on feedback. (It's also ok if you don't like = it at all.)=20 In that case, we'dd have to think of something else.=20 I started out with a Z80 design, but this 8088 seems much easier as it = has most of the 8085 signals available. (And =C3=8D've ordered the = hackaday PCB for a very nice low price. A total of 10 Euro including = shipment, so it can be used as a reference design.)=20 Using the memory expansion card on the SBC-85 design should also not be = very difficult.=20 =20 BR/=20 Guus Assmann=20 =20 Op 22 augustus 2020 om 17:31 schreef john@jjwhitney.com = :=20 Hi Guus: =20 I can not open the files you sent as I do not have the proper = schematic program. That said What I was thinking was a simple 8088 = circuit with the 8284 clock chip, 62256 32K ram, 27256 eprom with a = 74LS573 to decode the address bus. An 8251A USART is desired with it all = using Craig=E2=80=99s SBC-85 bus with the extra signals added to = accommodate the extra address lines of the 8088. It should all fit on a = board about 100mm X 100mm like the SBC-85. =20 I believe the V20 chip you use handles both 8085 and 8088 = instructions so that looks like a good possibility. As of today I do not = have the board design capabilities and if I did I am not very good at = board design. I can review any schematic if I can get them in a PDF = version so I can open it. Overall I am not looking for anything more = than a hobby edition and having it available as open source is = desirable. Let me know how I can help and it=E2=80=99s great to meet = another enthusiast. =20 Jack =20 From: guus.assmann@wolmail.nl = >=20 Sent: Saturday, August 22, 2020 9:57 AM To: craig.andrews@tessol-inc.com ; = john@jjwhitney.com =20 Subject: Re: SBC-88 =20 Hello, =20 Have been bussy. Sorry for not consulting first, so please regard this as a proposal. More information will follow. =20 BR/ Guus Assmann Op 22 augustus 2020 om 1:35 schreef craig.andrews@tessol-inc.com = : Hi Jack and Guus =20 By way of introduction, you have both expressed interest in developing = an 8088 version to the SBC-8x ecosystem. Guus has started the = development of a Z80 version so I have sent him the 8085 CPU board kicad = files as a starting point, I can also send these to you Jack. Since I = have no plans to create an 8088 CPU it would be fantastic if you two = wanted to work together on this. I suspect that if you create a = hackaday project you could find others to join since I have been asked = many times if I am planning an 8088, Z80, and 6502 versions, or if you = prefer I can create the hackaday project and you can join as team = members. The short answer is that I am not planning on developing any = other CPU board but strongly encourage others to add to the ecosystem = and will support that effort to the extent I am able. =20 I look forward to new hardware for the SBC-8x ecosystem and hope this = comes to fruition. =20 Best regards =20 Craig =20 =20 =20 =20 ------=_NextPart_000_0197_01D8C49E.58FE5750 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Hi Craig:

 

=C2=A0=C2=A0=C2=A0=C2=A0 I have a limited set of test = instruments so I may not be able to check everything effectively. I need = to dig up my frequency counter to see if the crystal is working. I may = have a bad batch of crystals so I will find another way to get the baud = rate signal to the board. I have some ideas on how I can check that = stuff and I will let you know what I find. Since both boards are doing = the same thing it may very well be the crystal on both boards is not = working.

 

Jack

 

From: SBC-85 = <craig@sbc-85.com>
Sent: Thursday, September 08, 2022 = 11:56 PM
To: john@jjwhitney.com
Subject: Re: SBC-85 = plus new project board

 

Writing = commands and getting response should be fundamental, you are right that = is the place to start.

 

Are you using 8251 or = 8251A?

 

You have I/o with the PPI, so Board decoding must be = ok but if you can confirm /CE with a scope or logic probe that would be = worth the effort.

Can you = put a scope or logic probe on and make sure /rd /wr reset A8 are the = same on the UART and PPI?

Do you have a good CLK at the UART?  The PPI = doesn=E2=80=99t need a CLK, but the UART needs it to = work. 

 

 



On Sep 8, 2022, at 3:26 PM, john@jjwhitney.com = wrote:

=EF=BB=BF

Hi = Craig:

 

     I had the chance to try the = SPIO board today and can not get the serial port to work. The other = ports work as expected but I get no response from the 8251 when I send = data to it. I used the confidence test to send data to the port and the = response back was all zeros where your documents show different = responses. When I do an input to the control register of the 8251 I get = only zeros back. I tried two different boards and 3 different 8251 chips = with the same results each time.

 

     I do not know what to try = next. Any suggestions?

 

Jack

 

From: craig@sbc-85.com <craig@sbc-85.com> =
Sent: Wednesday, September 07, 2022 6:28 PM
To: john@jjwhitney.com
Subject:<= /b> RE: SBC-85 plus new project board

 

Hi Jack, =

I see another tindie order including = the SPIO.    Are you still having trouble getting those = going properly? Maybe I need to take some time to look into it and see = what could be going wrong?  if you are having troubles, let me know = what you are seeing and maybe I can figure out what is going = on.

 

regards

 

craig

 

From: john@jjwhitney.com <john@jjwhitney.com> =
Sent: Sunday, August 7, 2022 1:14 PM
To: craig@sbc-85.com
Subject: = RE: SBC-85 plus new project board

 

Hi = Craig:

 

       Glad to hear you = are back at it. I never got the original bus monitor to work 100%, had = trouble with the single stepping, so I decided to try the new version of = the board. I really like the idea of having a front panel with flashing = LEDs. I retired last month and will be looking for things to keep busy = and building boards is something I enjoy, at least as long as I can see = up close.

 

     I never got the serial port = to work. I think it had to do with hand shaking, I gave it some thought = and when I try again I will tie CTS & RTS together on both ends and = see if that works. I haven=E2=80=99t look at the code in maybe two years = so it will take me some time to get back into it and know what = I=E2=80=99m doing.

 

     If you have an extra STD-bus = board I can take a look and see what I can do with it. I have no = experience with that interface so the board would be operated in stand = alone configuration. I watched the video you sent and will have to look = up the project to get additional info. Thanks for the offer and I hope I = can help with the project. Let me know if I can help down the = road.

 

Jack

 

From: craig@sbc-85.com <craig@sbc-85.com> =
Sent: Sunday, August 07, 2022 12:58 PM
To: john@jjwhitney.com
Subject:<= /b> SBC-85 plus new project board

 

Hi Jack, I = see you got another bus monitor board from tindie.

 

Did we = finish up this discussion / problem on the SPIO board or did I drop off = the edge of the earth?  I am trying to remember last august---since = august can be good flying weather, sometimes when I come back from a = long trip, I totally forget where I was

 

If you would = use it, I can send you one of the new STD-85 boards I just = finished.  it is STD-bus but it has a few fun features and I could = always use your help finding problems with the board / software / = documentation.

 

{93}= STD Bus 8085 Single Board Computer First Round of Testing--Getting to = know the STD-85 - YouTube

 

if you need = another project, I can toss it into the envelope.  Or, if  you = are looking for a real change of pace, I think I have one of my F8 = boards left I could send.

 

let me = know

 

best regards,

 

craig

 

From: john@jjwhitney.com <john@jjwhitney.com> =
Sent: Sunday, August 8, 2021 5:31 AM
To: 'craig = Andrews' <craig.andrews@tessol-inc.com= >
Subject: RE: SBC-88

 

Hi = Craig:

 

     My most recent projects = include a Z80 CP/M system based on the RC2014 platform as well as the = Glitch works 8085 CP/M system. I just got the Z80 working this weekend = and finding a lot of cool stuff from the 1980=E2=80=99s again. The = storage system is a 64MB compact flash drive and the 100 pin bus has = many different cards to add to it. The Glitch works 8085 is a bit more = limited but has some expansion capabilities. Over all I think your bus = structure is better and if you have thoughts of adding a compact flash = card for storage they are fairly easy to implement. Only problem is the = fine pitch surface mount card holder.

 

     One other project is I am = trying, yet again, to grow Bonsai trees. It is a fascinating hobby but = very challenging to start a tree from a seed and have it grow to a = sustainable size. I have had success in germinating a few trees only to = have them all die at some point, some lasting many months but all seem = to succumb to neglect. Maybe as I get in to retirement I will have more = time to pay attention to them.

 

     As for the needed = corrections, I still could not get the 8251 on the SP/IO board to work. = Might have something to do with CTS/RTS signals but I=E2=80=99m not = sure. I am looking forward to reviewing you future projects so please = let me help when you need a second pair of eyes. Stay healthy and = productive and I look forward to hearing from you soon.

 

Jack = Whitney

 

From: craig Andrews <craig.andrews@tessol-inc.com= >
Sent: Wednesday, August 04, 2021 11:48 = PM
To: john@jjwhitney.com
Subject:<= /b> Re: SBC-88

 

Hi = Jack, it is good to hear from you.  I am slowly getting back into = things but have not been working on electronics much.  For some = reason starting (and then finishing) projects seem like a major = hurdle.

 

If you have come across any things in the = documentation that I need to address, please let me know.  Those = are little projects that are easy for me to get = traction. 

 

I = cannot remember if I caught up on all corrections on the hardware like = the dangling ground you found on the serial port.  So let me know = if you are seeing any hardware problems too. =  

 

If you are looking for software projects, the version = of tiny basic on the sbc-85 site is still = incomplete.

 

yes, there is a lot of good, clean fun left in the = 8085 still yet.

 

What projects are you up = to?

 

Regards

 

Craig

 

On Aug 4, 2021, at 7:02 PM, john@jjwhitney.com = wrote:

=EF=BB=BF

Hi = Craig:

 

     Long time since we last = connected. So glad you are better now and wish you the best moving = forward. I was a bit worried since you went from a prolific poster to = nothing so suddenly. Sorry to hear about you contacting Covid-19, I hope = you are fully recovered or close to it. I know I asked about the 8088 = system before but now I=E2=80=99m hooked on the 8085 and built a few = different versions and having a lot of fun. Thanks for sending me down = that road as I have learned a lot along the way.

 

     Take care and keep me = informed of your next project. I wish you all the best.

 

Jack = Whitney

 

From: craig.andrews@tessol-inc.com= <craig.andrews@tessol-inc.com= >
Sent: Friday, September 11, 2020 7:43 = PM
To: john@jjwhitney.com
Subject:<= /b> RE: SBC-88

 

Just = discovered there is a mistake in the SBC-85 v2

 

Pin 5 of the = DB9 was left floating, that needs to be taken to ground

 

Regards

 

Craig

 

 

From: john@jjwhitney.com <john@jjwhitney.com> =
Sent: Sunday, August 23, 2020 6:51 AM
To: guus.assmann@wolmail.nl
Cc: craig.andrews@tessol-inc.com=
Subject: RE: SBC-88

 

Hi = Guus:

 

     I was able to look at the = items you sent. As for the buss structure I believe it will work as = described. The only change would be to change the TRAP pin to NMI and = connect the NMI pin to it. Both have the same function on their = respective CPU=E2=80=99s, just the naming difference.

 

     I downloaded the KiCad = program and am working on a new schematic for the 8088 circuit. It will = take me a while as I have to learn how the program works and how to make = it all look good.

 

     As for the circuit, I am not = a fan of using a Mega chip in support of the design. Reason is simple, I = am more of an old school design type. With the expansion capability of = the SBC-85 bus design I see the possibility of recreating an IBM clone = type of system if someone so desires. As with any old time CPU design = the question of why comes to mind and I say because there is a lot to = learn from the old stuff and it is far more simple to build than any new = concept.

 

     Give me a few days to = discover the KiCad program and I will try to get the CPU schematic = design done. From there I will look into a circuit board design as well. = I am a fan of using four layer PC boards even though they are more = expensive to build. I like the grounding effects the internal layers = provide and not having to route the power and ground lines helps keep = the number of feed through holes to a minimum. Please keep in mind that = these are my preferences and not an absolute for or against any other = design. By using a common bus it is possible for the universe of = potential designs to coexist and the use of various expansion boards to = be built. Keep in touch and thanks for the input.

 

Jack

 

From: guus.assmann@wolmail.nl = <guus.assmann@wolmail.nl> =
Sent: Saturday, August 22, 2020 1:46 PM
To: john@jjwhitney.com
Cc: = craig.andrews@tessol-inc.com=
Subject: RE: SBC-88

 

Hello = Jack,

 

Thanks for the reply.

Great that you're also willing to participate. =

I've done quite a bit of = PCB routing, so that's not the problem.

However it's always good if someone can check the = stuff I've done.

I've = printed the schematics from KiCad. (It's a free program, so you might = want to download it anyway.)

The schematics were taken from a Hackaday project. = I'll put those schematics in the mail as well. =

First thing that would = help a lot, is if you can compare the two schematics and also have a = look at the project on Hackaday.

 

Why did I select this?

Well, the hackaday project has been tested and has a = lot of software.

Using = the ISP interface on the Atmel Mega is not too complicated. =

But of course, one of the = Ram's can be replaced bay an Eprom.

And for that Hackaday project, there's a PCB, so I can = test that PCB and the one I've made.

It has an IIC bus for adding a RTC and an = SD-interface.

But I thing = the PCB-design is compattible enough to fit to the SBC-Bus. =

Also a lot of RAM and any = Eprom content can come from the Mega, fetching it from the SD-card. So = very flexible.

Still, I/O = can be added with the bus. And the RS232 interface can stay on as well. = All parts do fit the PCB. The only thing I've not put on (yet) is the = IIC-expander MCP23017.

This design doesn't need the 8284 clock chip and the = Mega does the Uart stuff.

 

One more thing I've done as preparation is make a = document on the expansion bus connector. We need to determine the = signals and what to add on the bus. The where to add it should be a bit = logical as well. But routing is not always so easy.... =

Could you also please = check these two documents. There's something missing still, I've not = added all the stuff.

 

Anyway, think about it.

And please don't hold back on feedback. (It's also ok = if you don't like it at all.)

In that case, we'dd have to think of something else. =

I started out with a Z80 = design, but this 8088 seems much easier as it has most of the 8085 = signals available. (And =C3=8D've ordered the hackaday PCB for a very = nice low price. A total of 10 Euro including shipment, so it can be = used as a reference design.)

Using the memory expansion card on the SBC-85 design = should also not be very difficult.

 

BR/

Guus Assmann

 

Op 22 augustus 2020 om 17:31 schreef john@jjwhitney.com: =

Hi = Guus:

 

     I can not open = the files you sent as I do not have the proper schematic program. That = said What I was thinking was a simple 8088 circuit with the 8284 clock = chip, 62256 32K ram, 27256 eprom with a 74LS573 to decode the address = bus. An 8251A USART is desired with it all using Craig=E2=80=99s SBC-85 = bus with the extra signals added to accommodate the extra address lines = of the 8088. It should all fit on a board about 100mm X 100mm like the = SBC-85.

 

     I believe the = V20 chip you use handles both 8085 and 8088 instructions so that looks = like a good possibility. As of today I do not have the board design = capabilities and if I did I am not very good at board design. I can = review any schematic if I can get them in a PDF version so I can open = it. Overall I am not looking for anything more than a hobby edition and = having it available as open source is desirable. Let me know how I can = help and it=E2=80=99s great to meet another enthusiast.

 

Jack

 

From: guus.assmann@wolmail.nl = <guus.assmann@wolmail.nl> =
Sent: = Saturday, August 22, 2020 9:57 AM
To: craig.andrews@tessol-inc.com= ; john@jjwhitney.com
Subject: = Re: SBC-88

 

Hello,

 

Have been = bussy.

Sorry = for not consulting first, so please regard this as a = proposal.

More information will = follow.

 

BR/

Guus = Assmann

Op 22 = augustus 2020 om 1:35 schreef craig.andrews@tessol-inc.com= :

Hi Jack and = Guus

 

By way of introduction, = you have both expressed interest in developing an 8088 version to the = SBC-8x ecosystem.  Guus has started the development of a Z80 = version so I have sent him the 8085 CPU board kicad files as a starting = point, I can also send these to you Jack.  Since I have no plans to = create an 8088 CPU it would be fantastic if you two wanted to work = together on this.  I suspect that if you create a hackaday project = you could find others to join since I have been asked many times if I am = planning an 8088, Z80, and 6502 versions, or if you prefer I can create = the hackaday project and you can join as team members.  The short = answer is that I am not planning on developing any other CPU board but = strongly encourage others to add to the ecosystem and will support that = effort to the extent I am able.

 

I look forward to new = hardware for the SBC-8x ecosystem and hope this comes to = fruition.

 

Best = regards

 

Craig

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