RE: Checking syntax for 1541 and more...
Date: 2007-09-10 10:48:36

Hallo allemaal,

First a question for all of you: has anyone a maller formatting routine
that I can use to replace the original one? I know JiffyDOS has one
AFAIK and I just hope someone can give me some onfo about it. Using a
smaller routine can free up some bytes I can use for another routine,
see below.
Thanks in advance!

Hallo Antitrack,

> Which hardware have you been using to read CF-cards?

A PC and a...... 1541 :)

The used hardware inside the 1541:
- a male IDE connector (from a scrapped PC)
- a 74LS139, 74LS245 and 74LS244

One half of the 139 generates the /RD and /WR signals with PHI2 and R/W
als input, the other half generates the two ChipSelect signals needed
for the IDE bus. Remark: so far I haven't found any reason or use for
the second CS signal so I probably will drop it in future designs.
The 245 buffers the data bus, the 244 the three addresslines and the
reset line.
The CS input of all parts is connected to O4 of the onboard 74LS42 thus
mapping the IDE drive at address $1000.

> Can you share the code?

I can but it is so simple that IMHO an example will do:

.eq IDEcs0		= $1000			; CS0
.eq IDEdata		= IDEcs0 + 0
.eq IDEerror	= IDEcs0 + 1
.eq IDEnumSec	= IDEcs0 + 2		; number of sectors
.eq IDElba0		= IDEcs0 + 3		; starts counting from
ONE !!!
.eq IDElba1		= IDEcs0 + 4
.eq IDElba2		= IDEcs0 + 5
.eq IDElba3		= IDEcs0 + 6
.eq IDEstatus	= IDEcs0 + 7		; when reading
.eq IDEcommand	= IDEcs0 + 7		; when writing

; Read very first sector from harddisk
		ldx	#1
		stx	IDEnumSec		; number of sectors
		stx	IDElba0		; start with sector 1
		stx	IDElba1
		stx	IDElba2
		lda	#$E0			; bit 6 = LBA mode!
		sta	IDElba3
		jsr	ReadIdeSector

		jsr	LedOn
		lda	#$20			; read sector
		jsr	SendCommand

		ldy	#0
		sty	IDEtmp0

JobReadSec	lda	IDEdata
		sta	(BUFPNT),Y
		bne	JobReadSec

		jsr	LedOff

;**  Send command to IDE
;- in:  A contains command
;- out: A contains error code
		sta	IDEcommand

		lda	IDEstatus		; ready?
		bmi	SendCommand010	; if not, -> wait

		and	#1			; error?

As you can see, it is just a matter of writing to or reading from some
registers. But to be honest, I haven't tested anything in ML yet. So far
I tested things in Basic by using M-R and M-W commands. And here I ran
into a weird problem that costed me quite some valuable time. I used a
256 MB CF card as HD simply because of the physical size and the fact I
didn't need an extra powersupply. But when checking a sector I found out
that the data was corrupted in a very weird but regular way and I was
only able to write 128 bytes to the card ( the LED on the adapter card
went out after 128 bytes). As I knew things had worked fine in the
beginning with a real HD I replaced the CF card and..... things worked
fine again! But my PC accepted the CF card as well W/O any problem.
Because I need this CF card for other things and having enough HD's
laying around, I decided to forget the problem for the moment.

At this moment I'm focussing on a Basic program that enables a standard
1541 plus my IDE inteface to exchange data with the HD. The idea is to
store a small ML program in a buffer using M-W (or a &-file) and
transferring data to/from the HD using another free buffer. But with a
bit of luck I can squeeze the program in the free spaces of the original
ROM. Then the only thing I have to tell the program is at which sector
of the HD it should start to write/read the data to/from.

I'm also working on a complete replacemant of the original ROM. I found
out that not needing the formatting and head moving routines I saved
about 2000 bytes. Again with a bit of luck I can squeeze the extra
routines for sudirectories inside these 2000 bytes.

    / __|__
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