Atari DOS 2.0 & disk drives...

[DavidMil]

Normally I use MY DOS with my 800, which sees all four drives, but last night I booted with an Atari 2.0 DOS disk.

The 800 would only see drives one and two. It gave me an immediate 160 error when I tried to access D3 or D4.

Thinking I might have a bad SIO cable from D2 to D3 I swapped cables around (from the 800 to D1 and D1 to D2)

with the cable from D3 to D4 and the 850. Again I got the same 160 error. Ok, next I removed D1 and D2 and

changed D3 to D1 and D4 to D2. Both worked just fine. Last test was to Change my original D1 to D3 and D2 to

D4. Guess what? Yep, same 160 error when attempting to access D3 or D4. I can only assume that Atari DOS 2.0

only supports two drives. Anyone else have this problem?

 

DavidMil

 

PS. It does the same thing on my 800XL and 130XE

[BillC]

http://www.atarimania.com/faq-atari-400-800-xl-xe-how-do-i-modify-atari-dos-to-support-more-than-two-drives_62.html

[DavidMil]

Thank you Bill,

My wife has pressed me into taxi service/baggage handler today for her Christmas shopping, but I'll see what results I get tonight.

I'll post the results tomorrow morning.

 

David

[DavidMil]

When I got home I tried the link that BillC suggested. It worked beautifully. And, by the way, the default

for Atari DOS 2.0 is two drives. The link explained how to change it to four drives. Thank you BillC for the

info. This bit of data goes into my folder of tips and tricks!

 

DavidM

Kingwood, Texas

[Gavin1968]

The above URL is not working any more, but anyone with this issue look up memory location 1802, this is where you poke to adjust the number of drives in Atari DOS.

 

1802 70A DRVBYT

The maximum number of disk drives in your system, the DOS 2.0 default value is two. The least four bits are used to record which drives are available, so if you have drives one, three and four, this location would read: 00001101 or 13 in decimal. Each drive has a separate buffer of 128 bytes reserved for it in RAM. If you have more or less than the default (two), then POKE 1802 with the appropriate number: 1 drive = 1 BIT 0 Binary 00000001 2 drives = 3 BITS 0 & 1 00000011 3 drives = 7 BITS 0, 1 & 2 00000111 4 drives = 15 BITS 0, 1, 2 & 3 00001111 This assumes you have them numbered sequentially. If not, POKE the appropriate decimal translation for the correct binary code: each drive is specified by one of the least four bits from one in BIT 0 to four in BIT 3. If you PEEK (1802) and get back three, for example, it means drives one and two are allocated, not three drives. You can save your modification to a new disk by calling up DOS and choosing menu selection "H." This new DOS will then boot up with the number of drives and buffers you have allocated. A one-drive system can save 128 bytes this way (256 if one less data buffer is chosen). See the DOS Manual, page G.87.   https://www.atariarchives.org/mapping/memorymap.php   Hope this helps someone else, it was a pain trying to remember this for me.