[Coco] Need a FD 502 controller that can accept 28 pin roms
sales at gimechip.com
Wed Oct 13 02:24:49 EDT 2010
Okay - I thought that was what Darren A was saying but wasn't sure.
----- Original Message -----
From: "Arthur Flexser" <flexser at fiu.edu>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Wednesday, October 13, 2010 1:15 AM
Subject: Re: [Coco] Need a FD 502 controller that can accept 28 pin roms
> That modification is only necessary because Extended ADOS-3 requires 16K
> EPROM space; for an 8K DOS, the FD502 works fine as is, even if the DOS
> in a 27128 or 27512, so long as the code is in the correct 8K of the chip.
> The relevant address line is grounded on the FD502, and the modification
> requires cutting a trace to un-ground it along with running a jumper wire
> the edge connector.
> On Wed, Oct 13, 2010 at 2:03 AM, Little John <sales at gimechip.com> wrote:
>> Cool. I was going by what I had read in the Extended ADOS-3 Manual which
>> If you have the Tandy FD-502 controller, you already have a 28-pin
>> however, the controller needs a minor modification in order to be usable
>> with a 27128 EPROM.
>> It then mentions how to get the instructions from SpectroSystems,
>> The instructions may also be found on Page 76 of the March 1989 Rainbow
>> magazine except that there is a typographical error: It is pin 26 not pin
>> that must be connected to the controller's edge connector.
>> But are you saying it can handle a 16K EPROM without modifications? or
>> you saying that it can use any 2764-27512, but only as an 8K device? Just
>> curious. I use 27256's for everything because I have a ton of them - I
>> burn an 8K image into the 27256 stacked 4 times - so it doesn't matter
>> status of the upper address lines or even if they are floating - it still
>> If HDB-DOS is only 8K then it would be fine without mods, but if you
>> a 16K DOS (like CoCoNet) it would need the mod - I think?
>> -John #1
>> ----- Original Message ----- From: "Darren A" <mechacoco at gmail.com>
>> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
>> Sent: Wednesday, October 13, 2010 12:24 AM
>> Subject: Re: [Coco] Need a FD 502 controller that can accept 28 pin roms
>> On 10/12/10, Little John wrote:
>>>> The FD-501 drives will work with the FD-502 controller (or pretty much
>>>> coco controller). I may be mistaken, but I believe that the FD-502,
>>>> having a 28-pin socket, is still only wired for an 8K eprom and the
>>>> additional address line will still need to be hacked into the socket
>>>> jumper wire. Can anyone else confirm this?
>>> The FD-502 will accept anything from a 2764 to 27512 without
>>> modification. For anything larger than a 2764, the code must be
>>> programmed into the upper-most 8K of the device.
>>> Coco mailing list
>>> Coco at maltedmedia.com
>> Coco mailing list
>> Coco at maltedmedia.com
> Coco mailing list
> Coco at maltedmedia.com
More information about the Coco