Re: Re: standalone code for bootstrapping

I dont understand why youre not taking advantage of the capabilities of the
hardware. Ever hear of something called a TIC (transfer-in-channel)? If you
write a chained IPL PSW/CCW, you can TIC back to track 0, and then figure
out what type of DASD you are on by SRCH to record* 4, then read record
4...

For Example (Borrowed from another program) -

IPLPSW     DC    XL8'0008000000000300'  EC MODE RESTART PSW
IPLCCW02 DC    XL8'0600027060000090'  RD DATA OF REC 2
IPLCCW03 DC    XL8'0800027060000001'  TIC TO 2ND IPL RECORD

And then ...

IPLCCW04 DC    XL8'0700029060000006'  SEEK TO TRK 0
IPLCCW05 DC    XL8'3100029660000005'  SRCH ID EQ FOR REC 4
IPLCCW06 DC    XL8'0800027860000001'  TIC BACK UNTIL FOUND
IPLCCW07 DC    XL8'0600030020004A00'  RD DATA OF REC 4

All of that is done in the CHANNEL :)

* Remember that in hardware language, a record is a block, so a SRCH to
record 4 in HW language is a SRCH to block 4 in software.

Joe

On Sat, Mar 16, 2019 at 5:40 AM kerravon86-/[email protected] [hercules-390] <
[email protected]> wrote:

>
>
> ---In [email protected], <kerravon86@...> wrote :
>
> > Actually I think the logic in sapstart should
> > be to start reading 32767 bytes from
> > head 0 record 4,
>
> I think rereading the first block will clobber
> modified code, so it will need to instead be
> read to a different location, like 32768, just
> to get the length and the start record
> properly figured out.
>
> BFN. Paul.
> 
>