Tape and Disk load speeds

[kool kitty89]

Standard Atari disk speed was 19,200 baud which when using a real drive gave about 1K/sec. This is terribly slow compared to what the SIO bus can do. Below is a video showing 127840 baud. I do a single pass copy of a 183K disk and get 21 sec for 180K read = 8.57KB/sec, and 24 sec for 180K write = 7.5KB/sec. Parallel based storage solutions such as a compact flash to IDE adapter can achieve 60K/sec when using a DOS based file system, or roughly 80K/sec when doing raw data transfers.

127,840 baud using SIO? (what's the bandwidth limits for SIO?)

 

The only Atari tape speed was SLOW. The FSK decoding was done in hardware so you couldn't bump too far past the stock 600 baud.

Yes, so you'd need a hardware solution to significantly enhance the tape speeds and several 3rd parties did end up producing such products: http://www.faqs.org/faqs/atari-8-bit/faq/section-20.html as JamesD posted earlier.

 

I'd imagine Atari themselves could have produced such an enhanced drive (maybe even supported it in the OS in later machines) and released corresponding carts with the loading programs. Though given the general push for disks in the US, that wasn't so much of an issue unless they really wanted to push into the low-end market. (would have been far more important in Europe, of course) Hmm, they also could have made a drive that worked at both the standard speed as well as high-speed decoding modes for full compatibility and the ability to load the fast loading program via tape at normal/slow speed and then switch to the high-speed mode. (and thus avoid the need for a cartridge containing the fast loading program)

 

But other than that, JamesD already mentioned data compression as another option, and of course the Commodore tape drives were considerably slower still at 300 baud (aside from custom loaders).

 

Did Atari BASIC load/save at 600 baud, or was that slower? (I'm trying to figure out the context of the "slow" BASIC tape loading comment I mentioned earlier)

 

Didn't synapse's tape version of dimension X, have high speed loading....I seem to recall it did (either that or it loaded in data in bigger chunks by using i believe modified DCB or IOCB routines)

Was that in software or requiring a fast loading tape drive?

[OldAtarian]

"c64 disk spped is probably similar to the A8"

 

What?!? I don't recall ever needing a fast loader to load anything from disk on my A8.

[kool kitty89]

"c64 disk spped is probably similar to the A8"

 

What?!? I don't recall ever needing a fast loader to load anything from disk on my A8.

Yes, we've established that statement by CarmelAndrews was false.

 

I haven't seen formal bitrate figures for the 1541, but it seems to be something below 1500 baud (comments about the CoCo tape drive being significantly faster), or possibly a fair bit below that given some other anecdotes. (claims that it was significantly slower than the Apple II's tape -1200 baud- or even some claiming it was slower than the Atari tapes -600 baud)

 

However wiki mentions the VIC/C64 DOS managing a 300 byte/s transfer rate (2400 bps) and 4 kB/s being the maximum achieved with the best fast loader applications. (that's 32,000 baud if accurate)

The Atari disk is 19,200 baud standard and capable of far more than that with fast loaders. (over 8 kB/s -64,000 baud)

 

Perhaps the CoCo anecdote is correct, but shoudl be in the context of double speed loading (close to 3000 baud) vs the normal 1500 baud rate. (vs 2400 baud for the C64's disk)

Edited September 30, 2010 by kool kitty89

[JamesD]

C64 Tape Loaders: link

[carmel_andrews]

No Kool K, the high speed stuff (if it was that) was embedded into the tape(re: dimension x)..i.e it was saved or recorded at high speed

[JamesD]

Some C64 loader speed measurements, see the link to the thread on the page for details (in German?).

http://www.c64-wiki.com/index.php/Comparison_of_fast_loaders

[kool kitty89]

No Kool K, the high speed stuff (if it was that) was embedded into the tape(re: dimension x)..i.e it was saved or recorded at high speed

Given all the other information, the only way that was possible was using compression with 600 baud stream (or close to 900 baud given some comments), the same way dial up internet can go beyond 56k.

Unlike other computers, the Atari 8-bit line had a hardware FSK decoder built into the tape drive (vs software decoding), so software solutions couldn't be used to improve physical data density on the tapes. (only modified/replacement tape drives/interfaces would address that for the A8)

 

 

Some C64 loader speed measurements, see the link to the thread on the page for details (in German?).

http://www.c64-wiki.com/index.php/Comparison_of_fast_loaders

I don't see any units for the measurements there.

Edited October 2, 2010 by kool kitty89

[TMR]

Some C64 loader speed measurements, see the link to the thread on the page for details (in German?).

http://www.c64-wiki.com/index.php/Comparison_of_fast_loaders

I don't see any units for the measurements there.

 

At a guess, it's multiples of stock 1541 transfer speeds so the first one (presumably using JiffyDOS at the C64 end and a stock 1541) is 3.7 times faster at formatting, 2.54 times faster at saving and 9.84 times faster for reloading.

[carmel_andrews]

Just curious whether the cassette version of Dimension X was released in the US, since the US didn't get many A8 cassette releases (compared to the UK/Euro markets)

 

And whether the US version was the Hi Speed version like the UK version

 

There were other A8 tape games that loaded data in larger chunks though (like all English software games, early EA, Novagen/synapse/synsoft and others) I think this was done by doing a custom written DCB/SIO routine to tell the computer to load in data in larger chunks per cassette sector/block

Edited October 2, 2010 by carmel_andrews

[kool kitty89]

Some C64 loader speed measurements, see the link to the thread on the page for details (in German?).

http://www.c64-wiki.com/index.php/Comparison_of_fast_loaders

I don't see any units for the measurements there.

 

At a guess, it's multiples of stock 1541 transfer speeds so the first one (presumably using JiffyDOS at the C64 end and a stock 1541) is 3.7 times faster at formatting, 2.54 times faster at saving and 9.84 times faster for reloading.

Yes, and they have a simpler overview of the general load speeds for C64 Tape and Disk fastloaders here: http://www.c64-wiki.com/index.php/Fast_loader

 

And given this: http://www.c64-wiki.com/index.php/VIC-1541 Wikipedia's 300 byte/s (2400 bps) rate for the normal loader is accurate.

http://www.c64-wiki.com/index.php/Datassette lists tape speeds of 60-70 byte/s (480-560 bps), but perhaps that full data rate, not taking the doubled data into account.

 

I wonder what the speed was like for the older VIC-1540 drive for the VIC 20.

[+Stephen]

Standard Atari disk speed was 19,200 baud which when using a real drive gave about 1K/sec. This is terribly slow compared to what the SIO bus can do. Below is a video showing 127840 baud. I do a single pass copy of a 183K disk and get 21 sec for 180K read = 8.57KB/sec, and 24 sec for 180K write = 7.5KB/sec. Parallel based storage solutions such as a compact flash to IDE adapter can achieve 60K/sec when using a DOS based file system, or roughly 80K/sec when doing raw data transfers.

127,840 baud using SIO? (what's the bandwidth limits for SIO?)

That is the physical limit. With careful coding, the screen can remain turned on (as shown in the copy program).