Z80 control board / EPROM Programming

[Mr. Phil]

A friend of mine and I are studying up on microprocessor interfacing and are
teaching ourselves about the Z80. We wired up the processor to an 8k static
RAM (6264), and 8k EPROM (2764), and we also have an 8255 for I/O. We have
but one problem,... we don't have an EPROM programmer!

Does anyone out there have a broken one (I can try to repair it) that
they're getting rid of? I can cover the shipping. We're trying to go as
inexpensive as possible. Any help would be greatly appreciated. Thank you!

-Phil

P.S. - Please send me an e-mail at [email protected] . Thanks!

 

[Hans Summers]

You could do it with a bunch of switches:
http://www.hanssummers.com/computers/newz80/intro.htm#SwitchBoard

Hans
http://www.HansSummers.com

 

[Mr. Phil]

That would be a heck of alot of switches. And tedious, no doubt. The
"test code" I wrote is only about 26 bytes, but if I go any larger, it would
be a problem. Imagine trying to program 2048 bytes into a ROM using
switches?

-Phil

 

[Terry King]

That would be a heck of alot of switches. And tedious, no doubt. The
"test code" I wrote is only about 26 bytes, but if I go any larger, it would
be a problem. Imagine trying to program 2048 bytes into a ROM using
switches?

You had SWITCHES?? You were so lucky! We only had stripped wires.... Two
people with 4 hands could do Hex pretty fast.

Sorry!

But this DOES remind me of getting Tiny Basic for my homebrew 6502
system in 1973. About 1 K, Came on paper tape. Didn't have a tape
reader. Brought it to the local college and ran the tape thru a
Teletype and printed it. Typed in each line of motorola hex dump.
Eventually got it to work and saved it to cassette recorder at 110 baud.

Jezum, I used to think Old Guys were so boring with their stories...

 

[Kev]

Just a thought but why not grab a battery backed RAM DS1210? that has the
same form factor as a 2716EPROM /6116 RAM.

Be faster than the EPROM.

KEv

 

[Gary Tait]

Just a thought but why not grab a battery backed RAM DS1210? that has the
same form factor as a 2716EPROM /6116 RAM.

Be faster than the EPROM.

KEv

You still have to progam it. (although if you have a legacy ISA bus
PS, and an I/O card with a BIOS rom socket, you could finesse it into
programming it.

Another thought is to get a modern PCI NIC that can accept a flashrom
and programming it on board.

You could use an LPC flashrom (almost directly uses a dozen lines or
so to program, as opposed to nearly 30 or so for a regular flash, but
reads like a normal flash).

You could build something like the Willem programmer.

 

[Madis Kaal]

RAM (6264), and 8k EPROM (2764), and we also have an 8255 for I/O. We have
but one problem,... we don't have an EPROM programmer!

http://home.quicknet.com.au/andrewm/eprom1/index.html
http://batronix.com/electronic/circuits/eeprommer.shtml

 

[Mr. Phil]

I like the battery backed RAM idea. At least it would work for prototyping.
I don't think I would want to use it for a final project. The way we have
it mapped out now is this: We have three input lines from a 74LS138 tied to
A15, A14, and A13 on the Z80. Thats mapping the 64k space in 8 separate 8k
segments. The first 8k segment
is wired to a 2764 (8k EPROM), the next 8k segment is wired to a 6264 (8k
RAM).
If I used a DS1210 without changing the memory mapping scheme, it would have
to mirror 4 times within that 8k space. (sigh).

I could eventually get around to building an EPROM programmer, but it took
my friend and I over a month just to get this far with the Z80 board.
Working with parts we already have on hand from scrap boards and junk
computers is easy,.. getting special parts is more difficult since we're
limited on funds. That's why I was asking if anyone out there had a broken
programmer that I can work on fixing.

-Phil

 

[Gary Tait]

I like the battery backed RAM idea. At least it would work for prototyping.
I don't think I would want to use it for a final project. The way we have
it mapped out now is this: We have three input lines from a 74LS138 tied to
A15, A14, and A13 on the Z80. Thats mapping the 64k space in 8 separate 8k
segments. The first 8k segment
is wired to a 2764 (8k EPROM), the next 8k segment is wired to a 6264 (8k
RAM).
If I used a DS1210 without changing the memory mapping scheme, it would have
to mirror 4 times within that 8k space. (sigh).

You could use a 64 Kbit ram chip stick a couple coin cells on it, and
make your own 8 K ram.

But that still begs the question, how to program it from a PC?

Except for the programming voltage generator, the hardware to program
an SRAM (and to that extent, a Flashrom), is no different than a full
EPROM programmer.

I could eventually get around to building an EPROM programmer, but it took
my friend and I over a month just to get this far with the Z80 board.
Working with parts we already have on hand from scrap boards and junk
computers is easy,.. getting special parts is more difficult since we're
limited on funds. That's why I was asking if anyone out there had a broken
programmer that I can work on fixing.

Most of the roll you own need no special parts. Yo use either latches,
counters, or shift registers to get address lines (99% of the plans
use one of the three I mentioned).

 

[Graham W]

I like the battery backed RAM idea. At least it would work for prototyping.
I don't think I would want to use it for a final project. The way we have
it mapped out now is this: We have three input lines from a 74LS138 tied to
A15, A14, and A13 on the Z80. Thats mapping the 64k space in 8 separate 8k
segments. The first 8k segment
is wired to a 2764 (8k EPROM), the next 8k segment is wired to a 6264 (8k
RAM).
If I used a DS1210 without changing the memory mapping scheme, it would have
to mirror 4 times within that 8k space. (sigh).

There's not much point in closing up the addressable space to be
adjoining.
Put the ROM at the bottom and start the RAM at 8000h i.e. half way up.
Now,
either of them has room to grow!

 

[Lewin A.R.W. Edwards]

but one problem,... we don't have an EPROM programmer!

Does anyone out there have a broken one (I can try to repair it) that

I guess you have an answer to your problem by now... but I happen to
have an old Needham's programmer sitting on my desk at work. It's an
internal ISA card type programmer, and I don't know what devices it
can burn (it has a 40-pin or 48-pin DIP ZIF socket on a long ribbon
cable) but if you think you can get it working, and you are willing to
cover postage, email me your address. It would probably only be $4 or
so to mail, it's light enough.

 

[Mr. Phil]

We want to try interfacing a UART to the Z80 CPU and attempt to hook it up
to a dumb terminal. Has anyone had experience with this? What would be the
best UART to use with the Z80? Any programming examples?

I found an interesting article on the web for an IDE interface
(http://www.zxplus3e.plus.com/interface.html) as well. Looks like something
I would like to try, but programming this would be a challenge since the
interface was originally designed for a Sinclair. I'm OK with hardware, but
software is my weakness.

Reading examples on the web is one thing, but it's nice to actually talk
with someone whos done it sucessfully.

-Phil