Re: [M100] CP/M has arrived for the M100

[Ken Pettit]

Hi Kurt,

I think you meant "Thanks John", right?  :)

File mode 4 is part of the SEEK invention ... 4=read/write mode

Ken

On 7/11/17 11:21 AM, Kurt McCullum wrote:

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 <mailto: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 <mailto:jho...@pobox.com>> wrote:




    On Tue, Jul 11, 2017 at 10:38 AM, Stephen Adolph
    <twospru...@gmail.com <mailto: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.