07/24/86: RE: EPROM PROGRAMMERS Re: Msg 10810 by Delphi, | Category: Delphi - Product Reviews & Announcement | 4 comments - (Comments are closed)


10866 24JUL86-0818 Product Reviews & Announcement


You clipped the right caps, and apparantly have successfully
moved the jumpers and replaced chips and added the jumper
for the MA7 line so as to get a 32K computer.

(note… it is preferable to use a ferrite bead, rather than
a 33 ohm resistor… but this is a minor point)

Now, to upgrade to 64K, you need to do a bit more stuff:

REMOVE the 74LS02 chip (U29 on the E board).
Bend up pins 4,5,and 6 on it. Also, remove the 74LS138 chip
(U11 on the E baord). Bend up pin no. 5 on it.

Now wire pin 4 of the 74LS02 to pin 5 of the 74LS138 (using long
enough wire so that when you plug the chiops back in their
sockets the wire will reach).

Run a short jumper wire from pin 6 of the 74LS02 to pin 8
of the 74LS02. Note that pin 8 of the 74LS02 will still
be pointing down and should still fit into the socket
when you plug the 74LS02 back in! So be careful
when you solder the wire to pin 8… make sure
to hook it near teh top of pin 8 and use minimum
amt of solder! Finally, run a longish wire from pin 5 of the
74LS02 all the way over to connect it to TEST POINT ONE on the
E board. This is an upright staking pin located near the 6809 chip,
lying between it and the 40 pin connector for the disk controller.

Plug the 74LS02 back in , and do likewise for the 74LS138.

Be sure the HixDgh / Low jumper is set to LOW.

You should now have a 64K (acutally 96K) CoCo.

Use CMEMTEST in the util section to check it out…
that is the best memory tester for the current coco ever written.

After you are sure all is well, I URGE you to REMOVE all the jumpers
one by one, and instead of jumpering the pins in question, SOLDER them.

For you will NEVER want to downgrade to 16K!!! And a solder connection
is more reliable than those jumpers… there have been cases of flakey
CoCo’s made flakey due to oxidation of teh jumper contacts.

Hope this solves yer problems!

Lemme know how it goes.


4 comments to RE: EPROM PROGRAMMERS Re: Msg 10810

  • pucc_unknown

    11392 4AUG86-0756 Product Reviews & Announcement
    RE: EPROM PROGRAMMERS (Re: Msg 10866)

    Well I was so glad when I heard about the new COCO III and got the
    information from the forum and the price sounded right and so I ran a print
    out of the information and took it with me to the Radio Shack Computer
    center and placed my order for a new COCO III and they told me the price
    was $299.95 and not $229.95 and I handed them the printout. The man went
    to his computer in the office and called up Dow Jones and printed out
    the Tandy news and sure enough the thing said $299.95. I hope they are
    dead wrong about that price. I sure want one but that price will slow me
    down a bit. What is going on out there ?
    Well I see that I put this one in the wrong place…Maybe I’ll get
    it right next time. I have been disconected three times this morning
    and end up back at the logon….

  • pucc_unknown

    11408 4AUG86-2247 Product Reviews & Announcement
    New CoCo 3 (Re: Msg 11392)


    The correct price for the new CoCo 3 is $219.95 (See Page 162, new catalog).
    Now, the new Hi-Res RGB Analog Color Monitor IS $299.95, so maybe they
    looked that up instead.

    At any rate, the CoCo 3 retails for $219.95.

    I hope I spelled your name right.

    — Jim Reed

  • pucc_unknown

    11427 5AUG86-0528 Product Reviews & Announcement
    RE: EPROM PROGRAMMERS (Re: Msg 11392)

    As usual, the folks at the Radio Shack Computer center
    are acting their incompetent selves. What else is new?
    The price is $229.95 for the base 128K CoCo 3.
    By the way, Tandy would prefer we refer to the CoCo 3
    as “CoCo 3” and NOT as “CoCo III” to distinguish the Tandy
    product line from Apple’s product line. In THIS matter,
    I tend to agree with their feelings!

    Go back and give it to those bozos!

    Anyway, the CoCo 3 shipment for RS stores and centers
    has not yet arrived in the US… the things are still
    on the boat coming in from the orient (persumeably Korea)
    where they are being assembled. Hope that boat does not sink!

    Look for your CoCo 3 ina about two weeks.


  • pucc_unknown

    11449 6AUG86-0003 Product Reviews & Announcement
    RE: EPROM PROGRAMMERS (Re: Msg 11392)

    The price our store got from Tandy was $219.95.

    I don’t know why your salesman was checking with Dow Jones because
    all the Tandy memos and even the 87 full line catalog has the correct
    price in it.