Some day I wanted to build a cartridge that goes into the SEGA SMS (also a z80 machine), with a 68000 chip.

I made prototypes really but cost was too high in the end to do it properly.

Still having various 68000 ICs around. But nowadays, you can get controllers with internal RAM+FLASH, so it is way a big effort to design for 68000. In the end, it can do about 1 million instructions/second, or about 100000 divisions/multiplications.

You simply get a certain amount of computing power for each $$$, and the gap is now 1:20 to 1:100.

One time I wanted to build a television interface, really some kind of a graphics adapter. It was way too much effort to complete the wiring for the prototype. It is technically doable, but the real degree of usefulness I get out in the end for each $$$, is much lower than using a modern mass produced color LCD.

I don't want to discourage you, possibly you have different motivation. Just saying, I owned various home computers, and honestly, to me they are just ewaste. I dont mean it personally, I had 2 SEGAs around until a few years ago, but then some day I just ditched all of it.

If you use it for learning BASIC, that's fine, I learned basic nearly 25 years ago on MSDOS 2.1

Old technology together with new technology- I program 16F5x in C language, these are very old PICs. Won't you guess they have no serial port and I mainly use them as serial I/O expanders via software protocol.

 

Some day I wanted to build a cartridge that goes into the SEGA SMS (also a z80 machine), with a 68000 chip.

I made prototypes really but cost was too high in the end to do it properly.

Still having various 68000 ICs around. But nowadays, you can get controllers with internal RAM+FLASH, so it is way a big effort to design for 68000. In the end, it can do about 1 million instructions/second, or about 100000 divisions/multiplications.

You simply get a certain amount of computing power for each $$$, and the gap is now 1:20 to 1:100.

One time I wanted to build a television interface, really some kind of a graphics adapter. It was way too much effort to complete the wiring for the prototype. It is technically doable, but the real degree of usefulness I get out in the end for each $$$, is much lower than using a modern mass produced color LCD.

I don't want to discourage you, possibly you have different motivation. Just saying, I owned various home computers, and honestly, to me they are just ewaste. I dont mean it personally, I had 2 SEGAs around until a few years ago, but then some day I just ditched all of it.

If you use it for learning BASIC, that's fine, I learned basic nearly 25 years ago on MSDOS 2.1

Old technology together with new technology- I program 16F5x in C language, these are very old PICs. Won't you guess they have no serial port and I mainly use them as serial I/O expanders via software protocol.

I use them for much more then Basic. It's just really hard to explain. I do very much get what you're saying! It's MUCH more convenient to use an emulator inside a laptop! Haha not to mention for space reasons too. I just for some reason do it anyway regardless of how much time or money I've wasted or well spent. One day it will probably come to end but not right now. All I really care about is the use my projects will get in the end. Not the amount of money I spent on them. I'm careful on what I decide to build.

With my motivation I have a couple friends from those days that help support and encourage me. They still got a lot of their old junk too.

Microcontrollers are defiantly much more convenient and again, it's amazing what you can do with them and for the price! But I hope that you will one day get to your vintage projects too.

 

We're all on this electronic forum website messing with electronics. I think we're all just a little strange

 

This forum isn't too bad- there is no gang of troublemakers, it is well moderated. But yes we have some strange members.

I still have one proto circuit with one 68000 IC, and I use a PIC as bootloader as well one 8bit RAM only then I mirror the upper bits via the PIC. Slow, but helps me do away with components.

I got it working to read/write the static RAM IC, and also I have two serial LED displays onboard. I magine if I breadboard the 8 digits LED display...

I also want to get it working some day, but the use is not clear, or let's say, with a PIC32 I get a far more powerful system with one single chip.

Of course going through all the 68000 opcodes was useful for learning too. One time I tried to write an assembler for it in Visual Basic. The parser was based on a binary tree, so a very fast assembler.

When I saw the effort neccessary to complete this Windows program and to do it properly, and to make some proto PCBs + test them, I stopped. The new 68K/PIC circuit was started more recently, about a year ago.

It's like printing, sometimes it is more convenient to use shops, or share a laser printer at an office, than to invest in a home printer. Sometimes you'd just write the address with a pen because it only takes a minute.

If you maintain it for hobby purpose, you can put as much effort as you like. there are relay computers, the BMOW, a clock from transistors, nixie clocks and all the like.

 

This forum isn't too bad- there is no gang of troublemakers, it is well moderated. But yes we have some strange members.

I still have one proto circuit with one 68000 IC, and I use a PIC as bootloader as well one 8bit RAM only then I mirror the upper bits via the PIC. Slow, but helps me do away with components.

I got it working to read/write the static RAM IC, and also I have two serial LED displays onboard. I magine if I breadboard the 8 digits LED display...

I also want to get it working some day, but the use is not clear, or let's say, with a PIC32 I get a far more powerful system with one single chip.

Of course going through all the 68000 opcodes was useful for learning too. One time I tried to write an assembler for it in Visual Basic. The parser was based on a binary tree, so a very fast assembler.

When I saw the effort neccessary to complete this Windows program and to do it properly, and to make some proto PCBs + test them, I stopped. The new 68K/PIC circuit was started more recently, about a year ago.

It's like printing, sometimes it is more convenient to use shops, or share a laser printer at an office, than to invest in a home printer. Sometimes you'd just write the address with a pen because it only takes a minute.

If you maintain it for hobby purpose, you can put as much effort as you like. there are relay computers, the BMOW, a clock from transistors, nixie clocks and all the like.

That's awesome! Good for you!

 

I have a Model 4P and rounded up a second one for the small repair shop I worked for. Their unit is used to interface with various 70's era hardware for test and repair. The fact that all address and I/O lines are available at a rear connector makes interfacing easy. Programming test routines in BASIC make it a dream. In fact, several of the manufacturers of the boards we repaired had BASIC listings in their manuals for testing, along with full schematics and parts lists. Gone are the good ol' days.

As for doing simple file transfers, you may want to join the site linked below. The format of the TRS80 files is not directly readable on a modern PC. The link below shows a way to interface to a SD card to transfer, but a TRS80 emulator needs to be running on the PC.

http://www.vintage-computer.com/vcf...6-How-to-build-a-cheap-HARDDISK-in-a-MODEL-4P

 

What you are attempting to do is perfectly doable, depending on how much time and effort you want to put into it.

There are two parts, hardware and software.
The hardware is the easy part.
How is the software going to connect with the hardware?
Are the UART drivers already written for you?

 

I had a Model I TRS-80 that I bought back in 1977; it had Level I basic in 4k ROM, 4K of RAM, a power supply, an RCA black & white TV set that was converted to a monitor by Radio Shack, and a tape cassette recorder to load/save programs and data from/to. It cost $530 USD. One of the first programs I bought was FS1, the first flight simulator - which makes perfect sense, because I was in a fighter squadron.

I upgraded the computer to 16k RAM, 16K Level II Basic, and added a numeric keypad (the keypad was $89 on top of the $150 RAM/ROM upgrade) These upgrades sans the keypad were necessary if one wanted to be able to upgrade to disk I/O. Originally, the computer wasn't capable of displaying lower case characters; I installed a hardware hack and wrote an assembler routine to allow access to the lower case letters, and provide caps lock capability. I also had to code up a keyboard debounce routine, as the Model I had notoriously bouncy keys. When I bought an Epson MX-80 w/Graftrax dot matrix line printer (another $500), I wrote a screen print routine activated by pressing JKL together that would print the exact contents of the screen on the printer, graphics and all. There were "JKL screen print" routines available, but those just printed the text portion.

After hearing about various reliability problems with the Radio Shack expansion interface (required to add any more RAM, RS-232, and disk drives; another $550) I decided to go with a Lobo Drives expansion interface; it was $430 so it was a good savings, and it was much more ruggedly built than the RS version. The only drawback was that I could only use LDOS with it; however that didn't turn out to be much of a limitation. The expansion interface had 32k RAM on board, so I was maxed out at 48k. There were provisions for RS-232, but I had to purchase the ICs and connectors, and wire everything up.

The original Radio Shack floppy drives were single sided, single density, had 35 tracks, and stepped at a 40ms rate - slow and small data storage; about 69K if my memory serves me right. I bought three BASF 5-1/4" drives at $470 for the lot; these were capable of stepping at a 12ms rate, were 40 track capable, and double density; when formatted as data disks, they had 174KB available. This seemed like a vast amount after fiddling with cassette tapes for years. I had three drives so that I could have the operating system disk in the 1st drive (drive 0), and copy disks between the other two drives - or have a program disk in drive 1 and a data disk in drive 2.

I bought a Hayes Smartmodem 300 (300 baud) for $300, and signed on to Compuserv around June of 1980. I made an airline reservation, and it cost me an extra ten bucks for the privilege - I figured it was going to take a while to catch on. That was the last I used the Compuserv account.

I later picked up a Model 4P, as I figured the Model I would become unreliable. Not long after, I picked up a PC clone, as that's all we used at work. Basically, the Models I and 4P went back in their boxes, and stayed there until I donated them to a technical school in Florida a couple of years ago.

 

What you are attempting to do is perfectly doable, depending on how much time and effort you want to put into it.

There are two parts, hardware and software.
The hardware is the easy part.
How is the software going to connect with the hardware?
Are the UART drivers already written for you?

Yes, there are drivers already written. If not, I have a manual on how to interface the UART in basic (which I'm perfectly fine with). I'm glad to hear that the hardware is the easy part! How would I go about building one and what IC's would I need?

I know many people say it's more worth it to use a floppy drive emulator (and it would be) but not only would I like the RS-232 card for file transfer, I would like to do some networking, like connecting to Ethernet through modems.

 

@SgtWookie - that's really awesome!! Also, flight simulators have come a long way since then