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Connectable to the TNS-NET network, the HC-08 enables system booting over the network.
Keyboard identical to TNS HC-16.
A total of 3 variants have survived:
For variants with two 2716 memories, the first is from address 0x0000, the second from address 0x1000 (i.e. there is a gap, apparently due to the plan for a larger circuit). The code first copies the contents to RAM, then the ROM is disconnected from the memory range.
It is possible to install an operating system on TNS-HC computers
either from 5 1/4" floppy disks directly attached to it,
or within the network via fast or slow
lines from another computer on the network.
By "fast line connection" we mean
connecting TNS computers with a coaxial cable using modules
UPP-NET.
By "slow line connection" we mean
serial current loop - channels A and B, controlled by the module
ASK or QASK.
Channel A current loop and fast line are controlled
common technical equipment and only depends on the settings
switches in the TNS-HC computer, which one will be controlled.
For this reason, they cannot be connected at the same time.
After turning on the computer, or resetting it, the bootloader
it announces by printing the opening header and then starts on its own
to find out if there is a floppy disk in any disk drive.
First it tests drive 0, then 1. If the disk really
finds, tries to install a special boot program from it,
which is stored in the reserved tracks of each system
floppy disks. If the disk found is indeed a system disk, it will boot
with the operating system. Otherwise, it will attempt to install
system failed (it "freezes").
If the bootloader is not found in any disk drive
diskette, it will ask where to boot the system from:
xxx asks where to boot from (A,B,L,X,Y,0-31 + Take) ?
The value "xxx" is the number of the given TNS-HC computer set
switch.
The user is expected to enter one of the following
options:
A - the bootloader will try to boot the operating system from disk
units 0.
B - the bootloader tries to boot the operating system from disk
units 1.
F - the bootloader will try to boot the operating system first
from disk drive 0. If not found in that drive
diskette, it will try to boot from drive 1 as well.
X - the bootloader switches to channel A of the current loop
Y - loader switches to channel B of the current loop
L - the bootloader switches to fast line. This state is
set by default.
dd - number under which is the remote computer from which
the system will be loaded, I know it in the network. It is entered
decimal in the range 0 - 31.
If you make a mistake when entering an option, you can correct yourself
using the [<-] key.
When booting from a remote computer, first is required
determine whether the operating system will boot from fast or
slow lines and possibly determine the channel of the current loop.
As mentioned, by default it is set to boot from
the fast line that is used most often. Line designation
done by choosing L, X or Y. The loader is thus prepared for
booting from the required line and again asks where from
should boot the operating system. However, it is now waiting for input
numbers of the remote computer from which the system will be booted.
The bootloader always tries to boot the operating system first
from floppy disks. However, so that we don't have to wait when booting from the line,
until the bootloader detects that they are not inserted in the disk drives
diskettes, we can press the desired option at the same time
by pressing the [RESET] button. After releasing both buttons,
the bootloader will try to boot the system as per our request.
Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989 Floppy 0 Floppy 1 003 asks where to introduce (A,B,0-31 + Take) ? 2 The line is connecting...ok reading the operating system ... ddd I'm handing over control to OS
After turning on the computer or resetting it, it displayed
loaded your opening header and started to find out,
whether floppy disks are inserted in the disk drives.
Follows this sequence though 5 1/4" units
they are not physically connected to the computer. The bootloader though
posted a query from where to start, from which we can conclude,
that it could not find the floppy disks in the drives. We request to implement
system through the default fast
lines from computer number 2. The loader first tried,
whether the connection can be established. He succeeded, that's why
started loading its own system file SYS.SYS. After
loading it, handed over control to the system.
2) Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989
Floppy 0 boots OSBOOT
OSBOOT V 2.01 (C) SWS/TPS Slusovice
Now the bootloader has found the system disk in drive 0
diskette, which can be recognized by the fact that it is from the diskette
succeeded in introducing a special OSBOOT boot program.
He first wrote his header and then on the diskette
looked for the system file SYS.SYS to which he passed po
introduction of management.
3) Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989
Floppy 0
Floppy 1 boots OSBOOT
The bootloader tested for diskettes in the drives. IN
it didn't find the disk in drive 0, it did in drive 1. It isn't
however, it's the system disk because it's bootable
failed to boot from it a special boot program
OSBOOT. The only solution to this error condition is
computer reset.
4) Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989
Floppy 0 boots OSBOOT
OSBOOT V 2.01 (C) SWS/TPS Slusovice
SYS.SYS not found
Even in this case, the diskette is not inserted in the drive
0 system because there is no system stored on it
SYS.SYS file.
5) Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989
Floppy 1 selection error
In this case, we are already in the process of resetting the computer
requested to boot the system from unit 1. They pressed
we are the [RESET] and [B] buttons at the same time. We can do that
infer that the bootloader tried to boot immediately
system from the floppy disk in drive 1 without prior to that
tested unit 0. However, because in this unit
there was no system disk, the bootloader displayed an error
reporting.
6) Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989
011 asks where to introduce (A,B,0-31 + Take) ? 5
The line is establishing a connection... - communication error
011 asks where to introduce (A,B,0-31 + Take) ?
The first thing that can be deduced from the texts in this example is
the fact that we already requested to boot the system during the reset
via the fast line. We pressed at the same time
[RESET] and [L] buttons. The bootloader tried to follow up
connection, which he failed to do. In this case
look for the fault directly on the line.
7) Loader TNS (FWLP) - in 1.2 JZD Slušovice 1989
Floppy 0
Floppy 1
008 asks where to introduce (A,B,0-31 + Take) ? 1
The line is connecting...ok
reading operating system ... 000
If the bootloader succeeds in establishing a connection, it will try
load the system file SYS.SYS. If the file
does not load (the counter remains zero), it is necessary
look for the fault directly on the computer where the system is from
introduce.
Chipselect signals are generated by 74154 (IC104)
| Output 74154 | I/O Range | Meaning / Circuit | Note |
|---|---|---|---|
| CS0# | 0x3C-0x3F | - | |
| CS1# | 0x38-0x3B | S2 | |
| CS2# | 0x34-0x37 | - | Supposedly S3 !!! |
| CS3# | 0x30-0x33 | S4 | |
| CS4# | 0x2C-0x2F | PFD OFF | |
| CS5# | 0x28-0x2B | PPIMAP | |
| CS6# | 0x24-0x27 | MAPF | |
| CS7# | 0x20-0x23 | DEFMAP | |
| CS8# | 0x1C-0x1F | OFF | |
| CS9# | 0x18-0x1B | FDC card | |
| CS10# | 0x14-0x17 | FDC card | |
| CS11# | 0x10-0x13 | PPI 1 - MHB8255A | |
| CS12# | 0x0C-0x0F | SIO - IC86 - UA8560D | Channel A (CTC1, Channel 0): TNS-NET / Fast Line, Channel B (CTC0, Channel 1): Serial Printer |
| CS13# | 0x08-0x0B | PIO - IC51 - UA855D | |
| CS14# | 0x04-0x07 | CTC1 - IC88 - UA587D | |
| CS15# | 0x00-0x03 | CTC0 - IC87 - UA587D |