High speed serial link

[SpeedGeek]

Originally Posted by clauddio

my A1200 have a 1220 turboboard 020/28mhz + 8mb ram
8m1.device works here but it is not safe like says in amiga explorer' docs....sometimes transfer corrupt files
btw,
another test I made was copy files direct to ram disk instead to hardisk...it doesn't make any difference in speed
also I changed workbench resolutions and colors from 256 to 4....also does not affect speed

Well obviously its not a CPU issue since a 40 Mhz 040 is much faster than a 28 Mhz 020. I justed discovered that if I nstall the OS3.9 ROM updates my A3000 can receive a little faster now (9-10 K CPS). Normally I don't bother with them because of the reboot delay at startup. One of these days I should get around to making a custom 3.9 ROM. I was not aware of any problems with 8n1.device. What protocol does windows explorer use?

[orange]

I could only get 38400 with no errors on unexpanded A500. its a shame, since some 8-bit computers can do more iirc.

@shrub
as already mentioned, you would be better off with parallel port. forget Explorer and use PC2Amiga.
make sure the cable is good, you need to make one. and that its not too long. it seems parallel port is more 'sensitive' than serial. with it you should get more than 50Kb/s, iirc

[illy5603]

I cannot remember the specifics but I remember having to eventually upgrade to an Amiga 3000T with a GVP I/O extender to run the serial port faster than 19200 with RTS/CTS for my BBS.

It was my understanding that an Amiga 500 (and likely the later models as well) could not do more due to the slow UART chips and the load placed on the CPU by RTC/CTS handshaking. I never tried any other driver save for serial.device for the stock RS232 ports so maybe the baudbandit.device allows it to run faster? The GVP came with it's own device driver which ran at I think 115200.

[Jope]

The Amiga doesn't have UARTs per se, the rs232 functionality is integrated into the CIA for some of the control signals (the even one) and Paula for the transmit and receive lines. The problem is, that if you run a too intensive display mode (amount of bit planes, horizontal refresh), the machine runs out of custom chip DMA time slots and the RS232 performance is degraded.

All Amigas have equal RS232 capability using the onboard port. A faster CPU alleviates the problem somewhat, but it's still mostly down to the display mode you selected.

Naturally a Zorro II board will not suffer from this problem, as it is not hooked up to the custom chip DMA bus.

[zipper]

115200 with 060 and RTG screen was the max for the standard device, just enough to keep a 56k modem happy.

[Ed Cruse]

Originally Posted by Jope

The Amiga doesn't have UARTs per se, the rs232 functionality is integrated into the CIA for some of the control signals (the even one) and Paula for the transmit and receive lines. The problem is, that if you run a too intensive display mode (amount of bit planes, horizontal refresh), the machine runs out of custom chip DMA time slots and the RS232 performance is degraded.

All Amigas have equal RS232 capability using the onboard port. A faster CPU alleviates the problem somewhat, but it's still mostly down to the display mode you selected.

Naturally a Zorro II board will not suffer from this problem, as it is not hooked up to the custom chip DMA bus.

Excuse me if I'm wrong here, but I believe the serial doesn't use any dma slots. The problem with receive speed is the interrupt code that services the serial port has to get the last byte from the hardware before the next byte is received. So increasing cpu speed would have a big affect, which I've personally noticed with my Amigas.

[Mad-Matt]

115200 was easy to maintain even on an 030/33 with artser.device (perhaps baudbandit too, I dont remember).

8n1.device was supposably the best, but I never had it work reliablly on any Amiga config (guru alot)

[illy5603]

Fascinating! Thanks for the clarification Jope! It certainly explains why the Zoro card with actual fast UART chips worked so well for the BBS when the internal serial on my 500 did not.

[SpeedGeek]

8n1.device is faster than baudbandit.device or artser.device. I get errors whether I use serial.device or 8n1.device at 115K baud. But Zmodem protrocol detects them and resends the packet. This what slows the effective transfer rate somewhat.

Also, I forgot to mention it helps to use a copymem speedup patch also. I've had good results with CMQ030 from Aminet.