Pulled this out of the trash at my college. Please share your microcomputer trainer stories in the comments for inspiration.
Posted by FortyFourForks@reddit | vintagecomputing | View on Reddit | 21 comments
DON'T PANIC! the EPROM has already been taped. but now that you're here id love to know about your experience using an early single board computer like this.
To give credit to my college, I didn't literally pull it out of the trash: my professor offered it to me because it was going to be recycled. I also found that nice technical drawing and also a bunch of manuals. it has definitely been modified (banana plugs, serial ports, expansion bus), but I'm not sure what they do. hopefully i will have time to test it out soon.
Intel System Development Kit 85 (SDK-85) is an 8085 based single board microcomputer trainer. This would have been used in a classroom to help students learn the basic theory and operation of microcomputers. these were first released in 1976, which definitely makes this the oldest model of computer in my collection, although im not sure when exactly this particular one was manufactured.
Using the luxurious 24 key keyboard and 6 character display, users could operate the built in monitor program to view and modify the computer's memory. this includes inserting instructions directly into memory using machine code to program it.
FlyByPC@reddit
Cool!
They're phasing out anything even remotely like assembly, where I teach. I understand the reasoning, but it's still a shame. Assembly teaches you how the actual processor works.
OldschoolSysadmin@reddit
The game "Human Resource Machine" got me into assembly programming.
OldschoolSysadmin@reddit
That is a historical treasure, and probably still an incredibly viable teaching tool.
FortyFourForks@reddit (OP)
i feel very lucky to own it: its a super unique part of computer history that a lot of people have a connection with, just look at all these stories in the comments! im looking forward to become part of that history by learning on it myself.
Enlightenment777@reddit
Z88DK is a Small-C-derived cross compiler for Z80 / 8080 / 8085 targets.
https://en.wikipedia.org/wiki/Z88DK
nmrk@reddit
I used this SDK-85 back when it was brand new. My university had a bunch of them in the microcomputer lab (which notably, was operated by the Astronomy and Physics department, not CompSci). I have all the manuals and documentation, but no hardware.
These were great little machines, other than having to punch in all your opcodes on the hex pad. Everyone in the class had to write ASM on paper, but I had a SOL-20 and I did it all in ALS-8 and then I had to write the code on paper (I didn't have a printer) and then bring it to the lab and punch it in. It was a huge advantage, I could test my code and see if it compiled, before bringing it to class.
FortyFourForks@reddit (OP)
im looking forward to the process of writing a program in asm and then converting it into hex and then punching them in although i imagine the novelty wont last long.
nmrk@reddit
We had one SDK-85 with a paper tape reader, but us lowly undergrads didn't have access to a paper tape punch.
I'm curious what that stuff is on the prototyping area. It ships with the prototyping area completely empty, the lab must have put those chips on for some specific purpose. I'm sure it won't affect normal operations.
FortyFourForks@reddit (OP)
The prototyping area has: 8k SRAM, a line receiver, a line driver, and some 7000 series logic chips. some quick google searching leads me to believe it was for connecting a data terminal.
adding a paper tape reader sounds like it could be a fun project
nmrk@reddit
We had one SDK-85 with a paper tape reader, but us lowly undergrads didn't have access to a paper tape punch.
I'm curious what that stuff is on the prototyping area. It ships with the prototyping area completely empty, the lab must have put those chips on for some specific purpose. I'm sure it won't affect normal operations.
TheMelwayMan@reddit
But can it run Doom???? 🤣
Future-Side4440@reddit
Yes probably, but very slowly. Someone sufficiently bored could whip up an ISA or PCI FPGA bridge.
For a device like this, the address space is a blank slate that you can do whatever you want with it.
Future-Side4440@reddit
Apparently if the window has been uncovered all this time, the EPROM is probably already blank. Though with the board this simple, recovery from nothing is not very complicated.
It likely consists of little more than a memory clear, and a routine to read the keypad and poke values into memory.
I bet with a map of the keypad logic, AI could whip up the monitor ROM for you.
weirdal1968@reddit
My tech school used ancient Heathkit 6800 trainers back in 1990. I was a C64 kid so I already understood coding/hardware but it was fun to use them and get As on every project.
https://www.retrotechnology.com/restore/et3400A.html
FortyFourForks@reddit (OP)
wow! i saw one of those in a computer museum recently
soulless_ape@reddit
Damn I used a similar model in highschool in the mid to late 90s
cch123@reddit
We had a 8085 we used and one week I was sick and missed the class about reverse counter. We were supposed to have it count up to 5 and back down to zero. I had no idea how to do it so I just made 6 show a 4, 7 show a 3, etc... I passed.
SpatialWaves00@reddit
Nice salvage and used a similar during my undergrad EE days for the “Microprocessor 1 &2” courses. The first class learned all about the 8080 architecture, ALU, and machine language programming. The second class was more assembly language. This would have been ~1990 and Intel development kits we used were already quite old and worn.
FortyFourForks@reddit (OP)
wow im surprised to hear they were used that late, but considering the current state of the electronics lab at my college maybe i shouldnt be.
SpatialWaves00@reddit
Yep and as mentioned they were already long in the tooth even by 1990. In fact only threw my textbook out a few years back from that class. Nothing like learning to program machine code as a fundamental to understanding the core of MPU operations.
kriebz@reddit
I did 8085 assembly in a microprocessors class, but we didn't have trainers. Just two different simulators with different bugs.