Posted By
repetto74
on 2018-05-05
07:39:37
|  PLUS4 / C16 Jiffydos PAL
Hi guys,
I have a PAL jiffydos bin file which I programmed 2x into a 27C256 eprom to test it on both machines. On the C16 the Jiffydos is working like a charm and loading speed via an SD2IEC is as fast as lighting!  . Strangely on the Plus4, which I believe has the same kernal, the prompt at power up is there but loading fails. Each time I try to load the SD2IEC menu I have a corrupted program loaded into memory and RUN will either pop up a screen monitor or display SYntax Error / Illegal Qty. Why does this not work on the plus4 considering the kernal is exactly the same? Neither to say that with the original PLus 4 kernal all is back to normal again. I tested this with a different eprom of same capacity but same problem. Is theres something I can do on the eprom to solve this? Heard about a pullup resistor or diode to be soldered on some pins?
Thanks
Rick
|
|
Posted By
siz
on 2018-05-05
09:38:04
| Re: PLUS4 / C16 Jiffydos PAL
It's definitely not a problem with the EPROM. Perhaps there is some other problem with your plus/4 that does not come forward when You use the stock ROM. You should try SJL264 Light to see if You can reproduce the problem.
For example a long time ago I had LEDs connected to the serial bus lines and even though most of the fast loaders worked I had problems with JiffyDOS and with Krills loader. As soon as I disconnected the LEDs all my problems went away.
|
|
Posted By
repetto74
on 2018-05-05
12:45:35
| Re: PLUS4 / C16 Jiffydos PAL
I was maybe thinking to use the Jiffydos BIN with Vice and see if it works with the emulator but I assume yes as it is working with the C16. How do I use this SLJ264 light?
|
|
Posted By
siz
on 2018-05-06
03:29:01
| Re: PLUS4 / C16 Jiffydos PAL
Like any normal fastloader for a 1541: load the run it. That makes the fast loader (it implements the JiffyDOS protocol) resident. Then you can load a program from SD2IEC.
|
|
Posted By
repetto74
on 2018-05-06
08:45:07
| Re: PLUS4 / C16 Jiffydos PAL
I do not catch how to load it. You mean using a real 1541 disk drive (for which I need to transfer the program to a real floppy) or just loading it with the SD2IEC with the original kernel on the Plus4?
|
|
Posted By
repetto74
on 2018-05-06
12:21:50
| Re: PLUS4 / C16 Jiffydos PAL
OK the loader is working and loading fast . Very good alternative at a hardware Jiffydos Thanks!
|
|
Posted By
MMS
on 2018-05-07
01:24:02
 | Re: PLUS4 / C16 Jiffydos PAL
AAAH, so you do NOT really need JiffyDOS EPROM into the machine! This is great news!
(anyhow, the Plus/4 PAL Jiffy was very hard to find)
Much easier to get a JiffyDOS ROM ready 1541 or 1571 drive. And use this fantastic piece of SW. Many thanks, BSZ!
Thanks for the tip too, I was not aware, or forgot it!
(too bad C= team was not that smart, and made the 1541 even slower than 1540. Imagine the better image of Commodore 8bit machines if they would be as fast as with Jiffy out of the factory, lighting fast program loading speeds).
One question remains: how it could be, that with JiffyDOS the loading becomes 10x faster on the serial IEC, while 1551 with the parallel bits it is still only 4.5x faster than the original 1541? The 1551 used it's own routines, why C= kept the slow bit-handling routines? With the much more data lines and direct memory access the 1551 should be ~20x faster with such fast routines, right?
|
|
Posted By
siz
on 2018-05-07
02:39:28
| Re: PLUS4 / C16 Jiffydos PAL
There is a post (in fact more than one) on BSZ's blog about 1551 (unfortunately in Hungarian only). To summarize: to send a byte from the drive to the computer needs a lot of handshake (more than sending from the computer to the drive!) and that makes KERNAL I/O much slower than it should be.
|
|
Posted By
MMS
on 2018-05-07
15:11:20
| Re: PLUS4 / C16 Jiffydos PAL
AAAAh, that blog. There was a lot of interesting HW evaluations there, including 1551 and SFD-1001. VVery detiulsed, beyond my humble konwledge.
OFF BTW BSZ also touched the Abdlib card with Yamaha chipset, and he connected it to the PC Parallel Printer port (he mentioned it could be easy to link it to 264 series too (I suppose he was thinking about the user port) )
|
|
Posted By
Hypex
on 2018-05-17
00:25:36
| Re: PLUS4 / C16 Jiffydos PAL
@MMS
They couldn't make it too much faster than the C64 1541 pop drive or it would have looked too superior.
|
|
Posted By
bubis
on 2018-05-17
04:32:20
| Re: PLUS4 / C16 Jiffydos PAL
Fun fact: BSZ's one chip TCBM replacement is much faster than the original bus.
We have a Bitfire transfer routine for 1551 that is 18.5 cpu cycles/byte fast but only works with BSZ's replacement chip, so we had to slow it down to 21 cpu cycles/byte.
|
|
Posted By
MMS
on 2018-05-17
16:01:33
| Re: PLUS4 / C16 Jiffydos PAL
|
|
