Thanks Steve.
I'll have to look at this. File mode 4 has be baffled since I was only aware of
three modes. 1-write, 2-append and, 3-read.
Since it already exists in LaddieAlpha I may just leave mComm alone,
Kurt
On Tuesday, July 11, 2017 11:06 AM, John R. Hogerhuis <jho...@pobox.com>
wrote:
Effectively, it allows simulating random "block" access on a TPDD file.
It's not the either the TPDD-1 or TPDD-2 sector access mode. It's an extension
Ken invented to the File Mode protocol.
Here's the Laddie code:
private void RequestSeekExtension() { // Seek (Ken
Pettit's proposal) for random access // file must have been opened
in mode 2 or 4 // ZZ, $09, $05, (type: Begin = 1, Current = 2, End =
3), Little Endian 32-bit offset, checksum
// decode seek type and offset var seekType =
(SeekType)Enum.ToObject(typeof(SeekType), (int)_lio.Req[4]); UInt32
offset = 0; for (var k = 8; k >= 5; k--) {
offset <<= 8; offset |= _lio.Req[k]; }
switch (seekType) { case SeekType.Begin:
_fo.Seek((int)offset, SeekOrigin.Begin);
break;
case SeekType.Current:
_fo.Seek((int)offset, SeekOrigin.Current);
break;
case SeekType.End:
_fo.Seek((int)offset, SeekOrigin.End);
break;
default: FormatStatus(0x10);
_state = State.Idle; break; } }
On Tue, Jul 11, 2017 at 10:54 AM, Kurt McCullum <kurt.mccul...@att.net> wrote:
John,
Is the SEEK command you are referring to similar to sector access mode or is it
an add on to the original TPDD protocol?
Kurt
On Tuesday, July 11, 2017 10:43 AM, John R. Hogerhuis <jho...@pobox.com>
wrote:
On Tue, Jul 11, 2017 at 10:38 AM, Stephen Adolph <twospru...@gmail.com> wrote:
NEC still needs a disk solution. Yes all RAM mode exists in both variants.
Other than a driver, I think external storage is already a solved problem.
LaddieAlpha already has a SEEK command which would allow it to be used for
random access, sector based storage.
The command could easily be added to mcomm too, I'd guess.
I am not sure but Ken might have already added that extension to NADSBox.
A very small portable storage solution on the expansion port would be better.
But you could certainly jerry-rig a Pi, LaddieAlpha and "juice pack" battery
today over serial.
What I think would be needed is to modify the CP/M code allow use the TPDD
protocol with SEEK extension.
-- John.
