All good things come to an end . . . .

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Joined: 11 Aug 2012 18:16

All good things come to an end . . . .

Post by Dave » 25 Jul 2014 21:32

Well folks, the well is almost dry,
the cupboard is nearly bare,
and as you can see,
the shelves are almost empty!
z80.jpg (64.17 KiB) Viewed 1850 times
That is, Lez's generous free gifts are now almost done, he won't be putting any more kits on ebay and has very little "stock" left.
He has however, kindly sent me a few more bits & pieces, so I have a few chips left.
If anyone would like something from the list below, let me know :

5 x Z84C0020PEC (Z80 DIP-40, 20MHz)
5 x Z84C0020VEC (Z80 PLCC-44, 20MHz)
5 x W27C512P (PLCC-32, 64k x 8 EPROM)
4 x CP82C55A-5Z (PPI, DIP-40)
3 x SN76489 (DIP-16, CSG)
8 x MAX232 (DIP-16)
1 x W27E512 (DIP600-28, 64k x 8 EPROM)
3 x MAX705 (DIP-8, WD/Reset)
4 x A623308A (DIP600-28, 64k x 8 SRAM)

First come, first served, responses by PM / e-mail

Martin A
Posts: 429
Joined: 09 Nov 2013 21:03

Re: All good things come to an end . . . .

Post by Martin A » 26 Jul 2014 10:34

That's a nice stock of parts, Seeing those PLCC parts, I wonder how small a PCB you could use these days and still fit on a complete(ish) MTX.

The BBC's been done in a little over 3" square.

Anyone up for a challenge??

Posts: 177
Joined: 14 Aug 2012 15:31

Re: All good things come to an end . . . .

Post by lezanderson » 26 Jul 2014 11:49

A ' Mini ' MTX512 could be produced relatively cheaply and on a small PCB.. The largest circuit being the V9958/V9938 part.

UM61512 SDIP32 64K SRAM
EPM7128SLC84 PLCC84 Glue logic
V9958/V9938 Video IC + DRAMs
SN76489 Sound Chip
8255 PIO PLCC44 for CF Card reader
MCU for keyboard reader
KIO for SIO/CTC/PIO functionality
Z80 BUS for daughter board

** Daughter Board ** Optional

AY-3-8910 Second Sound Chip
DS12887/DS12C887 RTC
AM9511 / NS32081 / D8087 Maths Processor
DS1245 or similar NVSRAM as RAM Disk ?

( This was originally my Colecovision Kit !) but it would make a very good MTX512 too !

Martin A
Posts: 429
Joined: 09 Nov 2013 21:03

Re: All good things come to an end . . . .

Post by Martin A » 26 Jul 2014 21:38

For a minimal MTX system, Maybe just a CTC instead of the KIO? it's physically smaller, and there won't be any issues with I/O ports being in the wrong place.

Not that the rom can't be modified to cope, but any hope of games etc working is lost if the KIO is occupying ports usually used for the basic hardware like the screen and keyboard.

The CPLD could possibly drive a keyboard matrix as well as IDE/CF

You'd be down to
Z80 (PLCC 44)
RAM (0.3" SDIP 32)
EPM7128 (PLCC 84)
V9958 (SDIP 64)
CTC (DIP 28)
Keyboard connector
And a few passives, clock etc

40 way IDE connector ?
DIN41612 expansion Connector ?

It won't fit into 3" square but maybe a single eurocard ?
Interestingly a 160mm eurocard fits the rails inside the MTX case, Ideal for internal expansions, so maybe as a PCB replacement too.

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