[Coco] [bruce#fanboy.net at 127.0.0.1: Re: Multi-Pak PAL equations for CoCo3?]

[John W. Linville]

Here is a message from the comp.sys.tandy newsgroup posted back in
November of 2003 -- hth!

John

----- Forwarded message from Bruce Tomlin <bruce#fanboy.net at 127.0.0.1> -----

> From: Bruce Tomlin <bruce#fanboy.net at 127.0.0.1>
> Newsgroups: comp.sys.tandy
> Subject: Re: Multi-Pak PAL equations for CoCo3?
> Date: Wed, 12 Nov 2003 11:15:10 -0600
> 
> In article 
> <bruceNS+usenet13-ABA3BC.20591415092003 at news-50.giganews.com>,
>  Bruce Tomlin <bruceNS+usenet13 at fanboy.net> wrote:
> 
> > Okay, I've got two multi-paks with the original PAL chip, and two 16V8 
> > PAL chips that I can program.
> > 
> > Does anyone have either the equations or a JEDEC file (even a raw JEDEC 
> > dump read from a chip would be great) for the updated PAL?
> > 
> > Unfortunately my programmer won't read any chip it can't program, and it 
> > doesn't know how to program any of the pre-V era PAL chips.
> 
> I had heard Tandy never set the security fuse on their Multi-Pak PAL 
> chips, but modern programmers won't even let you read fuse-PALs.  I 
> guess that means they're yet another form of "dead media".  So I got me 
> an ancient fuse-PAL programmer, installed it into an old ISA bus PC, and 
> read the chip with it.  It worked.
> 
> Here's a raw JEDEC dump of it:
> 
> 14L4*
> L0000
> 0000000000000000000000000000
> 0000000000000000000000000000
> 0000000000000000000000000000
> 0000000000000000000000000000
> 0110101110110101011001010110
> 1010011101110101011001010110
> 0000000000000000000000000000
> 0000000000000000000000000000
> 0110101110110101011101010101
> 1010011101110101011101010101
> 0000000000000000000000000000
> 0000000000000000000000000000
> 1010011111111111111111111111
> 1110101111111111111111111111
> 1111111011111111111111111111
> 1111111111101111111111111111
> *
> 
> And the pinout:
> 
> 1 = !(A15 & A14 & A13 & A12 & A11 & A10 & A9 & A8)
> 2 = A7
> 3 = A6
> 4 = A5
> 5 = A4
> 6 = A3
> 7 = A2
> 8 = A1
> 9 = A0
> 11 = R/!W
> 12 = E clock
> 13 = Q clock
> 14 => !G for data bus
> 15 => !I/O read
> 16 => !I/O write
> 17 => (unused output)
> 18 = !CTS - cartridge ROM select
> 19 = !SLENB - disable internal bus
> 
> The equations are:
> 
> pin 16 = (address = FF7F or FF9F) and write and E high and Q low
> pin 15 = (address = FF7F or FF9F) and read and E high
> pin 14 = address = FF40-FF7F or (address = FF00-FF3F or FF80-FFBF) or 
> SLENB low or CTS low
> 
> It looks like someone couldn't make up their mind on what address to use 
> for the cartridge select port.  It's also possible that the FF00-FF3F 
> was a goof from not including the A7 line when looking for FF80-FFBF.
> 
> The new equations should probably be:
> 
> pin 16 = address = FF7F and write and E high and Q low
> pin 15 = address = FF7F and read and E high
> pin 14 = address = FF40-FF7F or SLENB low or CTS low
> 
> This is the equivalent of removing the first terms of pins 15 and 16, 
> and the second term of pin 14.
> 
> I'll post a JEDEC file of this for the 16V8 later.
> 

----- End forwarded message -----

-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.