4 Feb
2007
4 Feb
'07
4:51 p.m.
some pcs didnt have dma. Tandy 1000...IBM
Peanut...Sanyo MBC-5xx too IIRC...
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Tony Duell wrote:
> I thought every PC (maaning IBM compatible) did
that. The floppy system
> in the PC. XT and ZT has a DMA channel associated
with it. You ask it to
> read some secotyors from the current track, it
does so and transfers the
> data into memory, then gives you an iterrupt when
it's done.
Well on some computers, like the COCO the IRQ only
is used
to end the cpu polling loop for the floppy.Since the
default
OS is CP/M err MSDOS I expect the hardware is not
used effectivly.
>
> I know for a fact that other tasks carry on
running on this (slow) linux
machine when
it's doing floppy drive operations.
-tony
5 Feb
5 Feb
2:39 p.m.
some pcs didnt have dma. Tandy 1000...IBM
Peanut...Sanyo MBC-5xx too IIRC...
Correct (well, it was option in the Tandy 1000, it was included on the
RAM expansion board).
I would also claim the Sanyo MBC-5xx was not a PC-compatible. Yes it ran
MS-DOS, but it wouldn't boot an IBM PC disk AFAIK.
Anyway, the fact that there are machines out there, even machines that
will boot an IBM PC disk, that don't have DMA doesn't invalidate my
comment that the IBM PC, XT and AT, and (most?) compattbles do use DNA to
transfer data from the floppy controller and can carry on processing
while a flippy disk operation is taking place.
-tony
6:30 p.m.
Tony Duell wrote:
Um, sure you're not thinking of the PCjr? I've put a Sound Blaster into
my Tandy 1000 and it works fine (requires DMA).
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/
some pcs didnt
have dma. Tandy 1000...IBM
Peanut...Sanyo MBC-5xx too IIRC...
Correct (well, it was option in the Tandy 1000, it was included on the
RAM expansion board). 
7:13 p.m.
Rumor has it that Jim Leonard may have mentioned these words:
Tony Duell wrote:
Um, sure you're not thinking of the PCjr? I've put a Sound Blaster into
my Tandy 1000 and it works fine (requires DMA).
Dunno... there were *lots* of Tandy 1000's... ;-) From memory, TX, SX, TL,
SL, TL/2, SL/2, (maybe a) TL/3, RL, RLX, HX, EX... I'm sure I'm missing a
few, as well...
The last two - the HX & EX, were all-in-one units with the keyboard
built-into the system unit, one floppy, minimal and specialized expansion -
maybe those didn't have DMA???
There's a picture of one about 1/2 way down, at the IckiPedia:
http://en.wikipedia.org/wiki/Tandy_1000
;-)
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
some pcs
didnt have dma. Tandy 1000...IBM
Peanut...Sanyo MBC-5xx too IIRC...
Correct (well, it was option in the Tandy 1000,
it was included on the
RAM expansion board).
8:47 p.m.
Roger Merchberger wrote:
The last two - the HX & EX, were all-in-one units
with the keyboard
built-into the system unit, one floppy, minimal and specialized
expansion - maybe those didn't have DMA???
Internally they had DMA as well (there were hard drive expansions for
them at some point).
I'm pretty sure you're thinking of the PCjr, which has the distinction
of being the only IBM PC compatible that is *slower* than the original
machine due to slow RAM (first 128K) and lack of DMA. Later upgrades
added faster RAM and DMA, but on stock delivery, it was slower.
But we love our bastard children :-)
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/
9:10 p.m.
----- Original Message -----
From: "Jim Leonard" <trixter at oldskool.org>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, February 05, 2007 11:47 PM
Subject: Re: TRS-80 Model I
Roger Merchberger wrote:
The Tandy 1000 HX and EX had DMA if you had the memory upgrade card
installed (also needed if you wanted to add any plus cards), but not stock.
The last two - the HX & EX, were all-in-one
units with the keyboard
built-into the system unit, one floppy, minimal and specialized
expansion - maybe those didn't have DMA???
Internally they had DMA as well (there were hard drive expansions for
them at some point).
I'm pretty sure you're thinking of the PCjr, which has the distinction
of being the only IBM PC compatible that is *slower* than the original
machine due to slow RAM (first 128K) and lack of DMA. Later upgrades
added faster RAM and DMA, but on stock delivery, it was slower.
But we love our bastard children :-)
--
6529
days inactive
6530
days old
5 comments
5 participants
participants (5)
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