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// license:BSD-3-Clause
// copyright-holders:Nigel Barnes
/**********************************************************************
Autocue RAM Disc
The RAM is accessible through JIM (page &FD). One page is visible in JIM at a time.
The selected page is controlled by the two paging registers:
&FCFE Paging register MSB
&FCFF Paging register LSB
256K board has 1024 pages &000 to &3FF
512K board has 2048 pages &000 to &7FF
**********************************************************************/
#include "emu.h"
#include "autocue.h"
//**************************************************************************
// DEVICE DEFINITIONS
//**************************************************************************
DEFINE_DEVICE_TYPE(BBC_AUTOCUE, bbc_autocue_device, "bbc_autocue", "Autocue RAM Disc");
//-------------------------------------------------
// device_add_mconfig - add device configuration
//-------------------------------------------------
void bbc_autocue_device::device_add_mconfig(machine_config &config)
{
NVRAM(config, "nvram", nvram_device::DEFAULT_ALL_0);
}
//**************************************************************************
// LIVE DEVICE
//**************************************************************************
//-------------------------------------------------
// bbc_autocue_device - constructor
//-------------------------------------------------
bbc_autocue_device::bbc_autocue_device(const machine_config &mconfig, const char *tag, device_t *owner, const XTAL &clock)
: device_t(mconfig, BBC_AUTOCUE, tag, owner, clock)
, device_bbc_exp_interface(mconfig, *this)
, m_nvram(*this, "nvram")
, m_ram_page(0)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void bbc_autocue_device::device_start()
{
/* ram disk - board with 8 x HM62256LFP-12 - 256K expandable to 512K */
m_ram = make_unique_clear<uint8_t[]>(0x40000);
m_nvram->set_base(m_ram.get(), 0x40000);
/* register for save states */
save_item(NAME(m_ram_page));
save_pointer(NAME(m_ram), 0x40000);
}
//**************************************************************************
// IMPLEMENTATION
//**************************************************************************
void bbc_autocue_device::fred_w(offs_t offset, uint8_t data)
{
switch (offset)
{
case 0xfe: m_ram_page = (m_ram_page & 0x00ff) | (data << 8); break;
case 0xff: m_ram_page = (m_ram_page & 0xff00) | (data << 0); break;
}
}
uint8_t bbc_autocue_device::jim_r(offs_t offset)
{
uint8_t data = 0xff;
if (m_ram_page < 0x400)
{
data = m_ram[(m_ram_page << 8) | offset];
}
return data;
}
void bbc_autocue_device::jim_w(offs_t offset, uint8_t data)
{
if (m_ram_page < 0x400)
{
m_ram[(m_ram_page << 8) | offset] = data;
}
}
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