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Hello, I've decided to put the design files for the PC-Retro into the public domain. The PC-Retro is a faithful reproduction of the original IBM 5150. My business MTM Scientific, Inc sold kits to build this motherboard starting in 2012. Over time it has become increasingly difficult to source...

Thank You both for that great information! Gives me a good direction to proceed and explore. Much appreciated. Michael

Hello, I am working on a homebrew TTL stack computer design using 74LS series chips. I recently created a single board version of the computer with an integral 50 channel bus. My computer is clocked at 1 MHZ. I have made provision for a bus-out connector, anticipating that I might want to...

This book is great! I recently wanted to add serial and parallel ports to my homebrew stack computer and the no-nonsense "here's how to do it" explanations had me up and running in no time using the venerable 8255 and 8251 IC's.

Of interest regards this topic is the AT BIOS Kit written in C by Annabooks. The files for the AT are floating around out there... There is a similar BIOS for the PC, but I have never been able to locate those files. https://archive.org/details/ATBIOS_Kit_Nov89

Here is a programming language checklist for people writing a new computer language. It's both funny and true... https://www.mcmillen.dev/language_checklist.html Here is an excerpt from the header: You appear to be advocating a new: [ ] functional [ ] imperative [ ] object-oriented [ ]...

Thanks Dave! Much appreciated. Michael

Hi, I have been reading about, and playing with a C Language Interpreter called "RUN/C Professional" as was offered by Lifeboat Associates in the 1980's, and as reviewed here: https://www.softwarepreservation.org/projects/interactive_c/bib/Unger-1987.pdf I was able to find a disk image of the...

Hi, It's been 3 months since I posted this WTB. Still looking! I am using my ACER 710 to write an assembler for my homebuilt LALU stack computer, and also cruising TELNET, thanks to Brutman's MTCP. A vintage ACER keyboard would be grand. Thanks. Michael

Hi, I am watching for an "ACER" badged Keyboard that has the 5 Pin large DIN connector with PC/XT output (Not AT). This would be before a "Windows" key was on the layout. Some of these keyboards have a slide switch on the underside to select PC/XT or AT. This is for an ACER 710, an IBM PC clone...

This is an IBM 5155 PC Luggable that is for sale and available for pickup only at the Monroe County Hamfest on Sunday, June 18th beginning at 7:30 AM. I have had this machine for over 20 years and don't remember where I got it. First attempt at boot showed a memory check that stalled, and 2nd...

Hi, I bought a batch of PROMDISK IV cards on EBAY back in 2016 and spent way too much time learning how to configure them. Here is a link to a zip file containing the information related to my adventures back then, including programming software. These cards are nice if you are working on bare...

Hi. This is a great discussion. Would someone be able to point to a resources that details how the EAE works? I have seen the circuit schematics, but would appreciate a higher level system level explanation. Thanks!

Thanks everyone for those great replies! I especially appreciate the links to other information, and the historical context. This same topic of Predication came up at another forum, and I pointed to the discussion above, here at the VCF. https://anycpu.org/forum/viewtopic.php?f=3&t=969 BTW...

I experimented with ChatGPT a few weeks ago. I had recently read part of a collection of personal letters written by Thomas Jefferson. I asked ChatGPT to summarize Jefferson's viewpoint on a arcane topic and it did great. Then I started to inquire about a atmospheric electrical phenomenon and it...

After giving it some thought, I ended up creating a lookup table for doing a full byte conversion. I put the ASCII character for the least significant nibble in my B register, and the most significant ASCII nibble in my A register. Then I created an ALU function with mnemonic HEX. (My ALU is...

Hi, I have been building and testing a homebrew 8 bit machine running at 1 MHZ called LALU (Lookup Arithmetic Logic Unit). One of my goals was to benchmark the machine using a method to calculate prime numbers up to 1000. Sometimes you will see this referred to as the Sieve of Eratosthenes...

Thanks for the replies! Here are 2 snippets of related code from the DEBUG source mentioned. I must have been mistaken that there is a bitwise trick for ASCII to HEX.

Hi, I am hoping someone can help with this... I seem to recall that there are some coding shortcuts for converting the ASCII character representation of a number to the actual number. For example the ASCII character Hx39 "Character for 9" represents the number decimal 9, and the ASCII...

Can anyone suggest a good reference which explains the operation of the ALU component of the 8088 CPU? Is that design out there somewhere? Thanks! Michael