[Coco] dload subroutines

[Darren A]

On 7/14/10, Little John (GIMEchip.com) wrote:

> You could use the OPEN command to open a #-3 file which is DLOAD. Then use
> the standard file access commands to talk to it like LINE INPUT #-2,A$ etc.
> Then after your done CLOSE #-3. I don't know how reliable this is and DLOAD
> only exists on the CoCo 1 and 2 - it was removed from the CoCo 3 - executing
> DLOAD on the coco3 performs a warmstart (or coldstart if you store a 0 at
> address 113).
>
> ----- Original Message -----
> From: "Jorge Renato Machin Ibarra"
>>
>> Hi!
>>
>> Do you know of any parameters that need to be set to call ROM's
>> subroutines 36284 (DLOAD) and 40962 and which data is returned?
>>

---

The OPEN statement does not accept -3 as a device number.  It will
issue a ?DN ERROR.

The subroutine at 36284 ($8DBC) is available on all CoCos with
Extended Basic, including the CoCo 3. It attempts to read a single
byte from the serial port.  If successful, the byte is returned in A
and the Z flag will be set. There are two variables in low RAM that
affect its operation:

DLBAUD  $00E6  (230)
Contains the delay value for the bit rate (176 = 300 bps;  44 = 1200 bps).

TIMOUT  $00E7  (231)
Indicates how long to wait for the byte before timing out (in
increments of roughly 2 seconds).

On the CoCo 3, these locations have been reused as HRMODE and HRWIDTH.
 You will need to save, setup and restore these locations around calls
to $8DBC.

Darren